Radar Device

ABSTRACT

A radar device, for example for automotive applications, comprises a radar circuit, an antenna device and a signal processing device, wherein the radar circuit is configured to transceive a first antenna signal and a second antenna signal, wherein the first antenna signal occupies a first frequency band and the second antenna signal occupies a second frequency band that is separate from the first frequency band, wherein the antenna device is configured to transduce the first antenna signal via a first antenna of the antenna device and the second antenna signal via a second antenna of the antenna device, and wherein the signal processing device comprises a ranging module that is configured to jointly process the first and second antenna signal to determine a distance to a target object irradiated by the antenna device.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to European Patent Application Number20155503.4, filed Feb. 4, 2020, the disclosure of which is herebyincorporated by reference in its entirety herein.

TECHNICAL FIELD

The present disclosure relates to a radar device, for example forautomotive applications, and a method for operating a radar device.

BACKGROUND

Radar devices are used in automotive applications to detect and locatetarget objects such as other vehicles, obstacles or lane boundaries.They may be placed at the front, at the rear or at the sides of avehicle. Such radar devices usually comprise a signal generator togenerate a radar signal, an antenna device for illuminating the targetobjects with the radar signal and for capturing the radar signalreflected back from the target objects and a signal receiver to analyzethe radar signal reflected back from the target objects. The informationextracted from the reflected radar signal may then be used for advanceddriver's assist system (ADAS) functions, such as emergency brake assist,adaptive cruise control, lane change assist or the like.

One information that may be extracted from the reflected radar signalmay be the distance to a target object irradiated by the radar device.For implementing ADAS functions, it is desirable to reliably detect andseparate different objects positioned within the field of view of theradar system. Such separation may be realized, inter alia, using therange information provided by the radar system. Increasing theresolution of distance determination or ranging thus contributes toimprove the detection efficiency of the radar device.

Accordingly, there is a need to improve the ranging informationavailable from radar devices.

SUMMARY

The present disclosure provides a radar device and a method foroperating a radar device according to the independent claims.Embodiments are given in the subclaims, the description and thedrawings.

In one aspect, the present disclosure is directed at a radar device, forexample for automotive applications, comprising a radar circuit, anantenna device and a signal processing device, wherein the radar circuitis configured to transceive a first antenna signal and a second antennasignal, wherein the first antenna signal occupies a first frequency bandand the second antenna signal occupies a second frequency band that isseparate from the first frequency band, wherein the antenna device isconfigured to transduce the first antenna signal via a first antenna ofthe antenna device and the second antenna signal via a second antenna ofthe antenna device, and wherein the signal processing device comprises aranging module that is configured to jointly process the first andsecond antenna signal to determine a distance to a target objectirradiated by the antenna device.

The present disclosure is based on the idea that the range resolution ofa radar device transmitting within different frequency bands viadifferent antennas may be increased by jointly processing the antennasignals transduced in the individual frequency bands. Typically, therange resolution of a radar device is inversely proportional to thebandwidth of the radar signal emitted by the radar device so that anincreased bandwidth leads to a smaller minimum target distance incrementthat is resolvable by the radar device and thus to an improved rangeresolution. Typically, the minimum resolvable distance dR is given by

${{dR} = \frac{c}{2 \cdot {BW}}},$

with c being the speed of light and BW being the bandwidth of the radarsignal.

The radar circuit of the radar device comprises all parts of the radardevice that process the antenna signals at the radar frequency used forilluminating the target objects. The radar circuit thus constitutes aradar front end of the radar device. The radar circuit may comprise asignal generator for generating the antenna signals and a signalreceiver for receiving and measuring the antenna signals. The radarcircuit may be configured as a transceiver comprising a transmitter, forexample the signal generator, and the receiver.

The radar circuit may handle or transceive the antenna signals bygenerating them at the signal generator based on at least one controlsignal and/or it may transceive the antenna signals by evaluating ormeasuring them at the signal receiver to generate at least one datasignal. Likewise, the antenna signals may be routed between the radarcircuit and the antenna device by sending them from the radar circuit tothe antenna device and/or by sending them from the antenna device to theradar circuit.

The signal generator may be configured to generate the antenna signalsbased on at least one control signal, for example based on at least onedigital control signal, that the signal generator receives from a signalprocessing device of the radar device. For generating the antennasignals from the at least one control signal, the signal generatorcomprises one or more transmit chains. Each transmit chain is configuredto convert one control signal into one transmit radar signal and tooutput this transmit radar signal to one signal port of the radarcircuit that is connected to an antenna port of the antenna device. Thetransmit radar signals generated by the transmit chains then provide thefirst and second antenna signal. For example, a first radar signalgenerated by a first transmit chain may comprise or constitute the firstantenna signal and a second radar signal generated by a second transmitchain may comprise or constitute the second antenna signal. In thiscase, the first and second antenna signal are routed between the radarcircuit and the antenna device via separate signal ports of the radarcircuit.

Alternatively, a radar signal generated by a single transmit chain maycomprise or constitute the first and second antenna signal, for exampleit may comprise the first antenna signal as a first signal portion andthe second antenna signal as a second signal portion. In this case, thefirst and second antenna signal is routed between the radar circuit andthe antenna device via a common signal port of the radar circuit. Theradar signal may consist of the first and second signal portion only orit may comprise further signal portions, for example a third signalportion covering a third frequency band.

Each transmit chain may comprise, for example, a digital to analogconverter (DAC) that is controlled by the control signal controlling thetransmit chain and/or one or several signal control devices that arelikewise controlled by the control signal and shape the transmit radarsignal generated by the transmit chain. Such signal control devices maybe configured as, for example, variable attenuators or amplifiers,variable phase shifters, and/or the like. The signal generator mayreceive the control signals from the signal processing device of theradar device. The control signals may, for example, be digital controlsignals.

For generating the at least one data signal from the antenna signals,the signal receiver comprises one or more receive chains. Each receivechain is configured to receive one receive radar signal via a signalport of the radar circuit that is connected to an antenna port of theantenna device, to convert the receive radar signal into one data signaland to output the data signal to the signal processing device. Thereceive radar signals received by the receive chains then comprise orconstitute the first and second antenna signal. For example, a firstradar signal received by a first receive chain may comprise orconstitute the first antenna signal and a second radar signal receivedby a second receive chain may comprise or constitute the second antennasignal. In this case, the first and second antenna signal are routedbetween the antenna device and the radar circuit via separate signalports of the radar circuit.

Alternatively, a radar signal received by a single receive chain maycomprise or constitute the first and second antenna signal, for example,it may comprise the first antenna signal as a first signal portion andthe second antenna signal as a second signal portion. In this case, thefirst and second antenna signal is routed between the radar circuit andthe antenna device via a common signal port of the radar circuit. Theradar signal may consist of the first and second antenna signal only orit may comprise further antenna signal as a further signal portioncovering a third frequency band, for example a third antenna signal as athird signal portion,

Each receive chain may comprise, for example, an analog to digitalconverter (ADC) that samples the radar signal and generates the datasignal outputted by the receive chain and/or one or more signalconditioning devices such as low noise amplifiers, programmable filters,mixers, and/or the like that shape the radar signal prior to sampling.The data signal representing the received radar signal may be a digitaldata signal.

The radar circuit may be configured to handle several independent radarsignals, for example to generate several independent transmit radarsignals from several independent control signals and/or to measureseveral independent receive radar signals to generate severalindependent data signals. The signal generator may then comprise severaltransmit chains, one transmit chain for each transmit radar signaland/or the signal receiver may then comprise several receive chains, onereceive chain for each receive radar signal. Each transmit chain isconfigured to generate an individual transmit radar signal from anindividual control signal, the individual control signals and transmitradar signals being mutually independent from each other. Likewise eachreceive chain is configured to measure an individual receive radarsignal received from the antenna device and to generate an individualdata signal from the respective receive radar signal, the individualreceive radar signals and individual data signals being mutuallyindependent from each other.

In general, each radar signal may comprise a multitude of signalportions, in particular more than two signal portions, each signalportion spanning a different frequency band and constituting a separateantenna signal. For example, the radar circuit may comprise threetransmit chains and four receive chains, each chain being connected toat least one antenna of the antenna device.

The individual transmit chains are coupled to the antenna device viaindividual transmit ports of the radar circuit and the individualreceive chains are coupled to the antenna device via individual receiveports of the radar circuit. Each transmit port is coupled to one of thetransmit chains of the radar circuit and is schematically locatedbetween the transmit chain and the antenna device and each receive portis coupled to one of the receive chains of the radar circuit and isschematically located between the receive chain and the antenna device.Each individual transmit port of the radar circuit may therefore beschematically located between the last signal control device of itsassociated transmit chain and the antenna device. Likewise, each receiveport of the radar circuit may be schematically located between theantenna device and the first signal conditioning device of itsassociated receive chain. The transmit ports and the receive portsconstitute signal ports of the radar circuit.

According to the present disclosure, an antenna signal is defined as thesignal that is transduced by an individual antenna of the antennadevice. Likewise, a radar signal is defined as the signal that is routedvia an individual signal port of the radar circuit and that is processedby a single transmit chain or a single receive chain of the radarcircuit. One radar signal may comprise a single antenna signal, forexample if only one antenna is connected to the signal port routing theradar signal, or it may comprise several antenna signals, such as thefirst and second antenna signal, for example if more than one antenna,such as the first and second antenna, is connected to a common signalport routing the radar signal. In the latter case, each antenna signalconstitutes a separate signal portion of the radar signal.

The individual radar signals and/or individual antenna signals mayexhibit individual and mutually independent signal parameters, such asphases, amplitudes, chirps, phase shifts, code sequences, for examplebinary phase shift codes, and/or the like. The mutually independentsignal parameters may constitute an orthogonal and linearly independentset of parameters. The individual and mutually independent signalparameters may amount to separability parameters that ensureseparability among the individual radar signals after reception, forexample for multiple input multiple output (MIMO) processing. Theseparability parameters may, for example, employ phase shift keying, forexample binary phase shift keying, or phase modulation, for examplebinary phase modulation, or the like.

The radar circuit may be configured in an integrated circuit. The radarcircuit may be configured in this single integrated circuit only or itmay be distributed over one or more additional integrated circuits. Theintegrated circuits may be phase coherently coupled to each other. Theintegrated circuits may be configured, for example, as monolithicmicrowave integrated circuits (MMICs). The individual ports of the radarcircuit may be physical connection points of one or several integratedcircuits of the radar circuit, for example of a MIMIC comprising theradar circuit. They also may be logical or conceptual ports that arelocated at signal lines between the transmit chains and the antennadevice and/or at signal lines between the receive chains and the antennadevice, respectively, for example in radar devices, in which individualcomponents of the radar circuit and the antenna device are integrated ona common carrier, like a common substrate.

The antenna device may transduce the antenna signals by converting theminto electromagnetic radiation that is emitted towards the target objectirradiated by the antenna device and/or it may transduce the antennasignals by receiving electromagnetic radiation scattered back by thetarget object and by converting the received electromagnetic radiationinto the antenna signals. The individual antenna elements of an antennamay be conductively coupled to their respective signal port of the radarcircuit. They also may be proximity coupled, for example via conductiveor inductive coupling. The individual antennas may be configured assubstrate integrated antennas such as microstrip patch antennas orslotted substrate integrated waveguide (SIW) antennas. They also may beconfigured as end-fire antennas, 3D antennas or metallized plasticantennas.

The first and second antenna of the antenna device differ in at leastone antenna parameter so that they create different antenna fields. Suchantenna parameters may be, for example, radiation pattern and/or gainand/or directivity and/or polarization and/or antenna position, or thelike. The first and second antenna signal may be transduced at differentand well defined physical locations on the antenna device that aregiven, for example, by the respective phase centers of the first andsecond antenna.

The first antenna is built of a first set of antenna elements thatcomprises at least one first antenna element and the second antenna isbuilt of a second set of antenna elements that comprises at least onesecond antenna element. The first and second set of antenna elements maybe disjunct so that the first antenna and the second antenna do notcomprise any common antenna elements and are spatially completelyseparate. The first and second sets of antenna elements may also containone or more common antenna elements, for example, the second antenna maycomprise all antenna elements of the first antenna. Finally, the firstand second set may be equal so that the first and second antenna areentirely built from common antenna elements. When comprising commonantenna elements, different antenna parameters of the first and secondantenna, for example different polarizations of the radiation patternstransduced via the common antenna elements, may be realized by differentfeeding schemes of the common antenna elements.

The individual antenna elements of the antennas may be conductively orproximity coupled to each other. They may be configured as, for example,several individual slots and/or several individual patches. Theindividual antenna elements may be coupled in series and/or in parallel.For example, the individual antennas may be configured as series fedantenna arrays or as corporate fed antenna arrays.

According to the present disclosure, an antenna of the antenna device isformed by all antenna elements of the antenna device that collectivelytransduce between a radiation field of the antenna in the far-fieldregion and its associated antenna signal handled by the radar circuit.Such an antenna may comprise a single antenna element or it may beconfigured as an array antenna that comprises a set of antenna elementsthat form individual radiating elements of the antenna and coherentlytransduce between the radiation field and the antenna signal. If theantenna is a receive antenna, the radiation field is an incomingradiation field that is captured by the antenna elements. If the antennais a transmit antenna, the radiation field is an outgoing radiationfield generated by the antenna elements.

The radiation field of an antenna has well-defined instantaneous fieldparameters in the far-field of the antenna like phase center, frequency,amplitude and the like. Likewise, each antenna has antenna parametersthat define the characteristics of the antenna and its radiation field.These antenna parameters may be a radiation pattern, polarization, gain,directivity, location of phase center or antenna position, and the like.

An antenna signal associated with a radiation field of an antennacomprises all signal components that are routed between the radarcircuit and the radar device that are transduced by the antenna andthereby represent the radiation field of the antenna. The signalprocessing device is configured to deduce from the antenna signal fieldparameters of the radiation field.

In general, the antenna device may comprise multiple sets of antennas,wherein all antennas of the individual sets transduce antenna signalsoccupying the same frequency band and wherein the frequency bands of theindividual sets mutually differ from each other. For example, theantenna device may comprise a first set of antennas transducing in thefirst frequency band, wherein the first set includes the first antenna,and a second set of second antennas transducing in the second frequencyband, wherein the second set includes the second antenna.

The antennas within each individual set of antennas may then transduceindividual sets of antenna signals, each antenna signal spanning thefrequency band of the corresponding set of antennas. For example, theantenna signals transduced by the antennas of the first set of antennasmay constitute a first set of first antenna signals and the antennasignals transduced by the antennas of the second set of antennas mayconstitute a second set of second antenna signals.

The individual antenna signals occupying the same frequency band mayexhibit mutually independent, for example mutually orthogonal,separability parameters that distinguish them from each other. Forexample, the individual first antenna signals may exhibit individualfirst separability parameters that distinguish them from each other andthe individual second antenna signals may exhibit individual secondseparability parameters that distinguish them from each other. As allfirst antenna signals are distinguishable from all second antennasignals by their frequency band, the same values of separabilityparameters may be used for one of the first antenna signals and one ofthe second antenna signals.

The radar device may be configured to adaptively activate the firstantenna by transceiving the first antenna signal and to adaptivelyactivate the second antenna by transceiving the second antenna signal.Analogously, the radar device may be configured to adaptively activateindividual sets of antennas, such as the first and second set ofantenna. For example, the radar device may adaptively activate the firstor second antenna or the individual sets of antennas, such as the firstand second set, depending on a traffic scenario in which the radardevice is being used. One such traffic scenario may be, for example,normal driving along a street and another traffic scenario may be, forexample, parking. The first antenna or first set of antennas may providea short-range radar for monitoring traffic within a first distance infront of the car, for example during parking, and the second antenna orsecond sets of antennas may provide a long-range radar for monitoringtraffic within a second distance, for example during normal driving. Thesecond distance may be longer than the first distance, for example by afactor of 2, 5, 10, or 100.

The radar device may be configured to cyclically activate the individualsets of antennas. Alternatively, it may be configured to simultaneouslyactivate the individual sets of antennas.

The radar device may be configured as a continuous wave (CW) radardevice and the antenna signals may exhibit a signal modulation that isused for determining the target distance. Such a signal modulation maybe a frequency modulation, a phase modulation, or the like. The radardevice may therefore be configured as a frequency modulated continuouswave (FMCW) or as a phase modulated continuous wave (PMCW) radar device.

The FMCW radar device may employ simultaneous transmit and receive pulseDoppler (STAR PD) signals. With these STAR PD signals, the first andsecond signal portion may each comprise a multitude of pulsed frequencysweeps over the first and second frequency band, respectively. Theindividual frequency sweeps may each exhibit constant slope, for exampleconstant falling linear slope. The signal processing device of the radardevice may then be configured to transform each individual sweep into aset of range bins by performing a first Fourier transform, for example afast Fourier transform, on the individual frequency sweeps. The signalprocessing device may further be configured to transform the individualrange bins into Doppler bins via a second Fourier transform, for examplea fast Fourier transform, whereby the second Fourier transform uses, fora given range bin, all signals for that specific range bin from allpulsed sweeps.

The first antenna signal may exhibit a first signal modulation and thesecond antenna signal may exhibit a second signal modulation. By jointlyprocessing the first and second antenna signal, the signal processingdevice may evaluate both the first and second signal modulation todetermine the distance to the target object. In general, each set ofantenna signals transceived by the radar circuit may exhibit anindividual signal modulation. The signal processing device may beconfigured to jointly process a subset of the antenna signals or allantenna signals to determine the distance to the target object. Thereby,the signal processing device may evaluate a subset of the individualsignal modulations or all individual signal modulations to determine thedistance to the target object.

The propagation delay of the antenna signals between the radar deviceand the target object may be determined from a modulation difference,such as a frequency or phase difference, between the antenna signalsreflected by the target object and a reference signal provided withinthe radar device. The reference signal may be, for example, the antennasignals that are being transmitted during reception of the reflectedantenna signals. To obtain the modulation difference, the signalprocessing device may be configured to mix the reflected antenna signalswith the corresponding reference signals.

If the signal modulation constitutes a frequency modulation, the firstantenna signal may exhibit a first frequency modulation that spans thefirst frequency band and the second antenna signal may exhibit a secondfrequency modulation that spans the second frequency band, so that thebandwidth of the first frequency modulation equals the first frequencyband and the bandwidth of the second frequency modulation equals thesecond frequency band. The bandwidth of a combined antenna signal thatis obtained by jointly processing the first and second antenna signalwith the ranging device then spans both the first frequency band and thesecond frequency band. The second frequency modulation of the secondantenna signal may be a frequency shifted version of the first frequencymodulation of the first antenna signal so that the instantaneousfrequency of the second antenna signal is given by adding theinstantaneous frequency of the first antenna signal and a constantfrequency shift.

The individual frequency modulations may be cyclically repeated. Theradar circuit may be configured to first generate the first antennasignal and to then generate the second antenna signal and the antennadevice may be configured to first transduce the first antenna signal andto then transduce the second antenna signal. When cyclically repeatingthe first and second frequency modulation, the first antenna signal andthe second antenna signal may be alternately generated by the radarcircuit and subsequently transduced by the antenna device.

The signal processing device may be configured to jointly process thefirst antenna signal and the second antenna signal by generating acombined antenna signal that spans both the first and second frequencyband and comprises the first and second antenna signal. The combinedantenna signal may be generated by concatenating the first and secondantenna signal. In general, the signal processing device may beconfigured to jointly process a multitude of antenna signals, forexample more than two antenna signals, each antenna signal spanning adifferent frequency band.

Additionally to jointly process the first and second antenna signal, thesignal processing device may be configured to separately process thefirst and second antenna signal to obtain target information that isonly accessible to one of the first and second antennas and not to theother one. The accessibility of such target information may, forexample, result from different antenna parameters and/or differentantenna fields of the first and second antenna, such as differentantenna positions and/or different antenna gains and/or differentsignal-to-noise ratios of the received antenna signals and/or differentantenna fields of view and/or different angular resolutions in azimuthaland/or elevation direction and/or different polarizations or the like.In general, the signal processing device may be configured to separatelyprocess the individual antenna signals of a multitude of antenna signalsto obtain target information that is only accessible to one of theantenna signals and not the others.

The first and second antenna signal may have a frequency gap in betweenthem. The frequency gap may amount to at least a tenth, at least afifth, at least a third or at least one half of the frequency span ofthe first and/or second frequency band. The frequency gap may amount toat most a tenth, at most a fifth, at most a third or at most one half ofthe frequency span of the first and/or second frequency band.Alternatively, the first frequency band may directly adjoin the secondfrequency band so that the first and second antenna signal exhibit nofrequency gap in between them.

The individual antenna signals are oscillating electromagnetic signals,such as microwave signals. The radar frequencies of the antenna signalsmay be at least 1 GHz, at least 30 GHz, at least 60 GHz or at least 70GHz. They may be at most 200 GHz, at most 100 GHz, at most 85 GHz, atmost 60 GHz or at most 40 GHz. The radar frequencies of the antennasignals may lie, for example between 31 GHz and 37 GHz or between 75 GHzand 85 GHz, or between 76 GHz and 81 GHz. The first frequency band maylie between 75 GHz and 78 GHz, for example between 75.5 GHz and 77.5GHz, and the second frequency band may lie between 79 GHz and 82 GHz,for example between 79.5 GHz and 81.5 GHz.

The radar device may be used in automotive applications to detect andlocate target objects such as other vehicles, obstacles or laneboundaries. Such target objects may be placed at the front, at the rearor at the sides of a vehicle

The radar device may be mounted to a vehicle. The radar device may beconfigured as an interior radar device that captures target reflectioninside a passenger compartment of the vehicle or as an exterior radardevice that captures target reflections from the outer environment ofthe vehicle, for example as a front radar or a side radar or a rearradar. The radar device may be part of a vehicle control system and maybe connected to a control device of the vehicle control system. Thecontrol device may be configured to perform advanced driver's assistfunctions, such as adaptive cruise control, emergency brake assist, lanechange assist or autonomous driving, based on the data signals receivedfrom the radar device. The control device and/or the signal processingdevice of the radar device may be configured as programmable logicdevices, such as programmable logic controllers, FPGAs, ASICs ormicroprocessors.

According to an embodiment, the signal processing device is configuredto separately process the first and second antenna signal to detect fromthe first antenna signal target reflections via a first propagationchannel and to detect from the second antenna signal target reflectionsvia a second propagation channel. By separately processing the first andsecond antenna signal, the target information obtained by the radardevice may be enhanced.

The first and second propagation channel may have different propagationchannel properties like polarization and/or antenna location, such aslocation of transmit antenna and/or location of receive antenna, and/orpath length towards the target object and/or field of view, for examplein elevation direction and/or in azimuthal direction, and/or radiationdirection, and/or detection range, and/or signal gain, and/or the like.The signal processing device may process the data from the individualpropagation channels to construct, for example, individual virtualantenna arrays, for example MIMO arrays.

If the antenna device comprises multiple sets of antennas transducing inindividual frequency bands, for example the first set of antennastransducing in the first frequency band and the second set of antennastransducing in the second frequency band, the signal processing devicemay separately process the individual sets of antenna signals toconstruct separate virtual antenna arrays. For example, the signalprocessing device may process all first antenna signals transduced viathe first antennas to form a first antenna array and it may process allsecond antenna signals transduced via the second antennas to form anindependent second antenna array. Each pair of transmit and receiveantenna within the individual sets may realize a separate propagationchannel. The signal processing device may resolve the individualpropagation channels within the different sets of antennas using theseparability parameters of the individual antenna signals transduced viathe antennas of the corresponding set. The signal processing device maydetermine the propagation and/or reflection properties of the individualpropagation channels by comparing the antenna signals that aretransmitted and received via the antennas associated with the individualpropagation path.

According to an embodiment, the first antenna signal comprises a firstfrequency sweep within the first frequency band and the second antennasignal comprises a second frequency sweep within the second frequencyband.

The first frequency sweep may span the first frequency band and/or thesecond frequency sweep may span the second frequency band. The firstand/or second frequency sweep may be a linear frequency sweep. The firstand/or second frequency sweep may have a single sweep direction, such asa rising direction and/or a falling direction. They also may have achanging sweep direction, like a triangular sweep direction. The firstand second antenna signals may comprise frequency sweeps having the sameslopes or they may consist of linear frequency sweeps having the sameslopes.

The propagation delay of the antenna signals and thus the distance tothe target object may then be determined from a frequency shift of theantenna signals reflected by the target object with respect the areference signal provided within the radar device. The frequency shiftof the received antenna signal with respect to the reference signal maybe determined by mixing the received antenna signal with the referencesignal to obtain an intermediate signal at a frequency corresponding tothe frequency shift and by determining the frequency of the intermediatesignal, for example using a Fourier transform operation. The resolutionwith which the distance to the target object can be determined is thengiven by the resolution with which the frequency of the intermediatesignal can be determined. Usually, the resolution for determining thefrequency of the intermediate signal is inversely proportional to thebandwidth of the antenna signals used to generate the intermediatesignals, such as to the combined bandwidth of the first and secondantenna signal.

According to an embodiment, a slope, for example a linear slope, of thefirst frequency sweep equals a slope, for example a linear slope, of thesecond frequency sweep. This facilitates determination of the targetdistance, as an intermediate signal derived from the first and secondantenna signal exhibits a well-defined frequency.

According to an embodiment, the radar circuit is configured totransceive a third antenna signal occupying a third frequency band thatis different from the first frequency band and the second frequencyband, wherein the ranging module is configured to jointly process thefirst, second and third antenna signal to determine the distance to thetarget object irradiated by the first, second and third antenna signal.

The third antenna signal may be transduced via at least one of the firstand second antenna. With this embodiment, at least one of the firstantenna or the second antenna transduces over a combined frequency bandspanning the first frequency band, the third frequency band and thesecond frequency band. Therefore, target objects that are located in theradiation field of both the first and second antenna are irradiated overthe complete combined frequency band and the complete combined frequencyband may be used to determine target properties of those target objects,like, for example, their distance and/or velocity. As the resolution fordetermining target properties, for example distance, is typicallyproportional to the bandwidth of the radiation used by the radar device,the target properties of target objects that are irradiated over thefull combined frequency band may be determined with higher resolutionthan target properties of target objects that are only irradiated withradiation within the first or second frequency band.

Alternatively, the third antenna signal may be transduced via a thirdantenna. The third antenna may be coupled to a separate signal port ormay be coupled together with the first and/or second antenna to a commonsignal port.

According to an embodiment, the third frequency band lies between thefirst and second frequency band. The third frequency band may, forexample, cover the entire frequency range between the first and secondfrequency band. This maximizes the bandwidth of the combined antennasignal used to determine the distance to the target object and thereforethe resolution with which the distance to the target object may beresolved. Alternatively, it may also be separated by a first frequencygap from the first frequency band and/or by a second frequency gap fromthe second frequency band.

According to an embodiment, the antenna device is configured totransduce the third antenna signal via both the first antenna and thesecond antenna. This enhances the signal strength of the combinedantenna signal and therefore the accuracy of the distance determination.The first and second antennas may be connected to the radar circuit viaseparate signal ports or via a common signal port.

According to an embodiment, the antenna device is configured totransduce the first antenna signal with a first polarization and totransduce the second antenna signal with a second polarization, whereinthe second polarization is different from, for example orthogonal to,the first polarization.

For example, the first polarization and the second polarization may belinear polarizations, and one of the first and second antennas maytransduce with horizontal linear polarization and the other one of thefirst and second antennas may transduce with vertical linearpolarization. The first polarization and the second polarization mayalso be circular polarizations, and one of the first and second antennasmay transduce with left-handed circular polarization and the other oneof the first and second antennas may transduce with right-handedcircular polarization.

Transducing the first antenna signal and the second antenna signal withdifferent polarizations improves the isolation between first propagationchannels comprising the first antenna and second propagation channelscomprising the second antenna, for example in MIMO configurations. Ifthe antenna device comprises a first set of antennas transducing in thefirst frequency band and a second set of antennas transducing in thesecond frequency band, all antennas of the first set may transduce withthe first polarization and all antennas of the second set may transducewith the second polarization. Therefore, all first propagation channelsconstructed from the first set the antennas may operate at the firstpolarization and all second propagation channels constructed from thesecond set may operate at the second polarization.

When evaluating the data signals generated from the received antennasignals in the signal processing device, the different polarizations ofthe first and second antennas may be used, for example, forclassification of the detected target objects. In this way, polarimetricproperties of the target objects may be detected and used during objectclassification by the signal processing device. This objectclassification may be performed, for example, by machine-learnedalgorithms that have been trained on data signals representing thepolarimetric properties of different training target objects.

If the antenna device transduces the first antenna signal with the firstpolarization and the second antenna signal with the second polarization,the first propagation channel may be defined by radiation having thefirst polarization and the second propagation channel may be defined byradiation having the second polarization. Apart from the polarization ofthe transmitted radiation, the first propagation channel and the secondpropagation channel may comprise the same propagation path from theradar device to a target object and back to the radar device. The firstpropagation channel and the second propagation channel may also comprisedifferent propagation paths between the radar device and the targetobject.

If the antenna device is configured to transduce the third antennasignal, it may be configured to transduce the third antenna signal witha third polarization that is different from the first and secondpolarization. The third polarization may be, for example, a linearsuperposition of the first and second polarization. For example, thefirst antenna may transduce with the first polarization while the secondantenna transduces with the second polarization and the third antennasignal may be transduced via both the first and second antenna. Thisresults in the third antenna signal having a polarization that amountsto a superposition of the first and second polarization. If the firstand second polarizations are orthogonal linear polarizations, the thirdpolarization may be linear polarization at an intermediate angle, forexample +/−45°, or elliptical polarization.

According to an embodiment, the signal processing device is configuredto process the first antenna signal to form a first virtual array ofantennas that resolves targets along a first direction and the signalprocessing device is configured to process the second antenna signal toform a second virtual array of antennas that resolves targets along asecond direction.

The second direction may be different from, for example orthogonal to,the first direction. The first direction may be the azimuthal directionand the second direction may be the elevation direction. Alternatively,the second direction may equal the first direction. The first and seconddirection may then be the azimuthal or the elevation direction.

The first virtual array of antennas may be constructed from the firstset of antennas that transduce in the first frequency band and thesecond virtual array of antennas may constructed from the second set ofantennas transducing in the second frequency band. The individualantennas of the first set may be displaced with respect to each otheralong the first direction and the individual antennas of the second setmay be displaced with respect to each other along the second direction.The virtual arrays of antennas may be constructed from the targetreflections received via the individual propagation channels establishedby the antennas of the first or second set of antennas.

The first virtual array of antennas is used to resolve individualtargets irradiated by the radar device along the first direction and thesecond virtual array of antennas is used to resolve the individualtargets along the second direction. The first and the second array mayhave, for example, the same angle resolution. The first and the secondarray may also have mutually different angle resolutions. The firstarray may comprise a different number of antennas than the second arrayand/or the antennas of the first array may be arranged with differentspacing than the antennas of the second array. For example, the firstarray may have a higher number of antennas than the second array and/orthe antennas of the first array may be arranged with a smaller spacingthan the antennas of the second array and the angle resolution along thefirst direction may be larger than the angle resolution along the seconddirection.

The virtual antennas of the first virtual antenna array may have evenfirst distances in between them. For example, the first distances mayamount to half the wavelength of a selected frequency within the firstfrequency band, for example to half the wavelength of the centerfrequency of the first frequency band. Analogously, the virtual antennasof the second virtual antenna array may have even second distances inbetween them. For example, the second distances may amount to half thewavelength of a selected frequency within the second frequency band, forexample to half the wavelength of the center frequency of the secondfrequency band. Alternatively, the first distance may equal the seconddistance. For example, the first and second distance may amount to thewavelength at a selected frequency that is in between the first andsecond frequency band, for example, at the center between a minimumfrequency of the first frequency band and a maximum frequency of thesecond frequency band or at the center between a maximum frequency ofthe first frequency band and a minimum frequency of the second frequencyband.

According to an embodiment, the first antenna has a first field of view,the first field of view having a first extent along a lateral direction,and the second antenna has a second field of view, the second field ofview having a second extent along the lateral direction, wherein thefirst extent is larger than the second extent.

This allows the radar device to perform different radar functions thatnecessitate different fields of view. For example, the data signals fromthe second antenna may be used by the signal processing device forlong-range radar (LRR) functions and/or adaptive cruise control and/oremergency brake assist, and the data signals from the first antenna maybe used for mid-range radar (MRR) or short-range radar (SRR) functionsand/or lane change assist, and/or cross traffic detection, and/orparking assist.

If the antenna device comprises the first set of antennas transducingthe first frequency band and the second set of antennas transducing thesecond frequency band, all antennas of the first set may have the firstfield of view and/or antennas of the second set may have the secondfield of view along the lateral direction. First propagation channelsconstructed from the antennas of the first set then comprise firstpropagation paths that are located within the first field of view andsecond propagation channels constructed from the antennas of the secondset then comprise second propagation paths that are located within thesecond field of view. Besides the different propagation paths, the firstand second propagation channels may additionally differ by thepolarization of the first radar signal and the second radar signal.

To realize a small field of view, the second antenna may comprise amultitude of antenna elements that are placed next to each other alongthe lateral direction and form a phased array that narrows the beamsolid angle of the second antenna in the lateral direction. The firstantenna may comprise a multitude of antenna elements that form a largerbeam solid angle than the antenna elements of the second antenna, forexample, due to the first antenna having a smaller number of antennaelements than the second antenna.

According to an embodiment, the antenna device is configured to capturetarget reflections of the first antenna signal from target positionswithin a first range and to capture target reflections of the secondantenna signal from target positions within a second range, wherein thefirst range is smaller than the second range. By activating the first orsecond antenna, the radar device may therefore activate antennaconfigurations having different target ranges.

If the antenna device comprises the first set of antennas transducingthe first frequency band and the second set of antennas transducing thesecond frequency band, all antennas of the first set of antennas may beconfigured to capture target reflections within the first range and allantennas of the second set of antennas may be configured to capturetarget reflections and the second range.

According to an embodiment, the second antenna comprises antennaelements of the first antenna. The second antenna may comprise only apart of the antenna elements of the first antenna or it may comprise allantenna elements of the first antenna. Besides the antenna elements ofthe first antenna, the second antenna comprises additional antennaelements that do not form part of the first antenna. Transducing thesecond antenna signal via a second antenna that comprises at least partsof the antenna elements of the first antenna and additional antennaelements allows to transduce the second antenna signal within adifferent, for example narrower, solid angle than the first antennasignal. Therefore, the field of view of the antenna device may bedifferent, for example narrower, in the second frequency band than inthe first frequency band. The additional antenna elements may bepositioned symmetrically on both sides of the antenna elements of thefirst antenna.

Alternatively, the antenna device may be configured to transduce thesecond antenna signal only via additional antenna elements and not viaantenna elements of the first antenna. The first and second antennasthen form dedicated and spatially separated antennas only transducingthe first and second antenna signal, respectively.

According to an embodiment, a first antenna element that is part of thefirst antenna and a second antenna element that is part of the secondantenna are both coupled to a common signal port of the radar circuitand the radar device is configured to route both the first antennasignal and the second antenna signal via the common signal port betweenthe radar circuit and the antenna device. Furthermore, the antennadevice is configured to transduce the first antenna signal via the firstantenna element and to transduce the second antenna signal at least viathe second antenna element. The first and second antenna signals routedvia the common signal port constitute first and second signal portionsof a radar signal routed via the common signal port. This increases thenumber of individually addressable antennas and thus the number ofpropagation channels available for signal processing by sharing a commonsignal port of the radar circuit among two or more individual antennasof the antenna device.

The antenna device may be configured as a frequency selective antennadevice that transduces antenna signals occupying the first frequencyband via the first antenna element and not via the second antennaelement and that transduces antenna signals occupying the secondfrequency band at least via the second antenna element. The radarcircuit may then be configured to activate dedicated antennas, such asthe first antenna or the second antenna, by varying or switching itsoperating frequency band. Therefore, the full bandwidth of the radarcircuit that is routed via the common signal port may be shared amongtwo or more antennas.

Frequency selectivity of the antenna device may, for example, berealized by employing a frequency selective first antenna and afrequency selective second antenna that are directly and simultaneouslycoupled to the common signal port. It may also be realized by couplingthe first and second antenna to the common signal port via a signalrouting device such as a frequency selective multiplexer or a switchingdevice that selectively couples the first antenna or the second antennato the common signal port. Frequency selectivity may also be realized bycoupling the first antenna via a first filter and/or the second antennavia a second filter to the common signal port, wherein the first filterpasses the first frequency band and blocks the second frequency band andwherein the second filter passes at least the second frequency band.

The first antenna may be configured to only transduce the first antennasignal and not the second antenna signal by suppressing transduction ofthe second antenna signal compared to the first antenna signal by atleast 10 dB, at least 20 dB, at least 30 dB, at least 40 dB, or at least50 dB. Likewise, the second antenna may be configured to only transducethe second antenna signal and not the first antenna signal bysuppressing transduction of the first antenna signal compared to thesecond antenna signal by at least 10 dB, at least 20 dB, at least 30 dB,at least 40 dB, or at least 50 dB

The common signal port may be a transmit port of the radar device andthe first and second antenna may be transmit-antennas of the antennadevice. Alternatively, the common signal port may be a receive port ofthe radar device and the first and second antenna may bereceive-antennas of the antenna device.

In general, a multitude of antennas that include the first and secondantenna may be coupled to the common signal port of the radar circuit.The radar signal generated by the radar circuit and routed via thecommon signal port may then comprise as individual signal portions amultitude of antenna signals, for example one antenna signal for everyantenna connected to the common signal port. In particular, more thantwo antennas may be coupled to the common signal port and the radarsignal may comprise more than two antenna signals. The individualantenna signals may each occupy a separate frequency band. The antennadevice may be configured to transduce each antenna signal via a separateassociated antenna of the antenna device.

In total, several or all ports of the radar circuit may be configured ascommon signal ports and may be simultaneously coupled to an associatedfirst antenna radiating in the first frequency band and to an associatedsecond antenna radiating in the second frequency band. Each individualradar signal that is generated by the radar circuit and that is fed to acommon signal port shared by two or more antennas may have a firstantenna signal within the first frequency band and a second antennasignal within the second frequency band, both antenna signals beingrouted via the common signal port.

For example, all signal ports of the radar circuit may be configured ascommon ports and the radar circuit may generate all radar signals with afirst antenna signal occupying the first frequency band and a secondantenna signal occupying the second frequency band. Alternatively, atleast one, but not all signal ports of the radar circuit may beconfigured as common signal ports and at least one radar signal maycomprise both a first and a second antenna signal, but at least oneother of the radar signals may comprise a first antenna signal onlyand/or at least one other of the radar signals may comprise a secondantenna signal only. The first and second antenna signals of the radarsignals share the bandwidth of their common signal port and transmit orreceive chain of the radar circuit that is connected to their commonsignal port.

The signal processing device may be configured to separate the firstantenna signal and the second antenna signal from each combined radarsignal received via a common signal port, for example by filtering outthe first frequency band to obtain the first antenna signal and byfiltering out the second frequency band to obtain the second antennasignal. Filtering may be performed by analog filtering prior to samplingand/or by digital filtering after sampling.

If the radar circuit comprises an integrated circuit, the common signalport may be configured as an external connection point of the integratedcircuit. Frequency selectively coupling the connection point to thefirst and second antenna then effectively doubles the individualantennas and propagation channels that are addressable via theconnection point forming the common signal port.

With all embodiments, the first antenna and the second antenna may beconfigured to radiate the first signal portion and the second signalportion from the same physical location on the antenna device. To thisend, the first antenna and the second antenna may be formed by a dualfrequency antenna that is resonant both in the first frequency band andin the second frequency band. Such a dual frequency antenna may be fedby a common signal line carrying both the first and second signalportion.

Alternatively, the first antenna and the second antenna may beconfigured to radiate the first signal portion and the second signalportion from different physical locations on the antenna device. To thisend, the individual antennas may be configured as separate antennas thatare located at different physical locations of the antenna device.

In general, the individual antennas coupled to the radar circuit mayalso contain a set of antennas that are configured to radiate individualantenna signals from the same physical location and another set ofantennas that are configured to radiate individual antenna signals fromseparate physical locations on the antenna device. For example, twoantennas may be configured to radiate their respective antenna signalsfrom the same physical location and two further antennas may beconfigured to radiate their respective antenna signals from separatephysical locations.

In another aspect, the present disclosure is directed at a vehicle withthe radar according to the present disclosure. Insofar, all embodimentsand effects that are disclosed in connection with the radar device alsoapply to the vehicle of the present disclosure and vice versa.

In another aspect, the present disclosure is directed at a method foroperating a radar device, for example for automotive applications, theradar device comprising a radar circuit, an antenna device and a signalprocessing device. The method comprises: transceiving a first antennasignal and a second antenna signal with the radar circuit, wherein thefirst antenna signal occupies a first frequency band and the secondantenna signal occupies a second frequency band that is separate fromthe first frequency band, transducing the first signal portion via afirst antenna of the antenna device and the second signal portion via asecond antenna of the antenna device, joint processing of the first andsecond antenna signal with a ranging module of the signal processingdevice to determine a distance to a target object irradiated by theantenna device.

The method may be performed, for example, by the radar device of thepresent disclosure. Insofar, all embodiments and effects that aredisclosed in connection with the radar device also apply to the methodof the present disclosure and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a first embodiment of a radar device according to the presentdisclosure;

FIG. 2 a transmission of first and second antennas of radar devicesaccording to the present disclosure;

FIG. 3 a time dependence of frequencies of radar signals generated bythe radar devices according to the present disclosure;

FIG. 4 a second embodiment of a radar device according to the presentdisclosure;

FIG. 5 a signal routing device of the radar device according to thesecond embodiment;

FIG. 6 an alternative embodiment of the signal routing device;

FIG. 7 another alternative embodiment of the signal routing device;

FIG. 8 a first antenna and a second antenna inductively coupled to acommon signal port;

FIG. 9 a first antenna, a second antenna and a further antenna seriallycoupled via filter elements;

FIG. 10 a first antenna and a second antenna configured as waveguideantennas and serially coupled via a filter element;

FIG. 11 a third embodiment of the radar device according of presentdisclosure;

FIG. 12 a placement of antennas of the third embodiment of the radardevice;

FIG. 13 a placement of antennas of the second embodiment of the radardevice;

FIG. 14 a fourth embodiment of the radar device of the presentdisclosure;

FIG. 15 differing fields of view of first and second antennas of anantenna device according to the present disclosure;

FIG. 16 a placement of the first and second antennas generatingdiffering fields of view;

FIG. 17 an alternative placement of the first and second antennasgenerating differing fields of view;

FIG. 18 a signal processing device for the radar devices according tothe present disclosure;

FIG. 19 an alternative transmission of first and second antennas forradar devices according to the present disclosure;

FIG. 20 bursts of a radar signal that may be used with antennas havingthe transmissions shown in FIG. 19;

FIG. 21 a further embodiment of a radar device according to the presentdisclosure;

FIG. 22 a further embodiment of a radar device according to the presentdisclosure;

FIG. 23 an alternative embodiment of the radar device of FIG. 22;

FIG. 24 an antenna device for the radar devices of the presentdisclosure;

FIG. 25 an alternative embodiment of the antenna device of FIG. 24;

FIG. 26 an alternative embodiment of an antenna device for the radardevices of the present disclosure;

FIG. 27 an alternative embodiment of an antenna device for the radardevices of the present disclosure;

FIG. 28 an alternative embodiment of a radar device according to thepresent disclosure;

FIG. 29 another alternative embodiment of a first and second antennacoupled to a common signal port for an antenna device of the presentdisclosure;

FIG. 30 an alternative embodiment of the first and second antennacoupled to the common signal port shown in FIG. 30;

FIG. 31 a method according to the present disclosure: and

FIG. 32 a vehicle equipped with a radar device according to the presentdisclosure.

DETAILED DESCRIPTION

FIG. 1 depicts a radar device 1 having a radar circuit 100, an antennadevice 200 and a signal processing device 120. The radar circuit 100comprises a signal generator 105 having a first transmit chain 125 and asecond transmit chain 126. The first transmit chain 125 is coupled to afirst common transmit signal port 130 and the second transmit chain 126is coupled to a second common transmit signal port 131.

Each common transmit signal port 130, 131 is coupled to a first antenna211 and a second antenna 221 of the antenna device 200, the firstantennas 211 and the second antennas 221 each being placed at differentlocations on the antenna device 200. The first transmit chain 125 isconnected to the signal processing device 120 to receive a first controlsignal 121 and the second transmit chain 126 is connected to the signalprocessing device 120 to receive a second control signal 122.

Based on the first control signal 121, the first transmit chain 125generates a first transmit radar signal 10 comprising a first signalportion 11 occupying a first frequency band and a second signal portion12 occupying a second frequency band. The first transmit radar signal 10is routed via the first common transmit signal port 130 to the antennadevice 200 and the antenna device 200 is configured to selectivelytransduce the first signal portion 11 of the first transmit radar signal10 via the first antenna 211 coupled to the first common transmit signalport 130 and to selectively transduce the second signal portion 12 ofthe first transmit radar signal 10 via the second antenna 221 coupled tothe first common transmit signal port 130.

Based on the second control signal 122, the second transmit chain 126generates a second transmit radar signal 15 comprising a first signalportion 16 occupying the first frequency band and a second signalportion 17 occupying the second frequency band. The second transmitradar signal 15 is routed via the second common transmit signal port 131to the antenna device 200 and the antenna device 200 is configured toselectively transduce the first signal portion 16 of the second transmitradar signal 15 via the first antenna 211 coupled to the second commontransmit signal port 131 and to selectively transduce the second signalportion 17 of the second transmit radar signal 15 via the second antenna221 coupled to the second common transmit signal port 131.

The individual first signal portions 11, 16 constitute first antennasignals transduced via the first antennas 211 and the individual secondsignal portions 12, 17 constitute second antenna signals transduced viathe second antennas 221. The individual first signal portions 11, 16 ofthe first and second transmit radar signal 10, 15 are radiated by theindividual first antennas 211 towards a target object 3 and theindividual second signal portions 12, 17 of the first and secondtransmit radar signal 10, 15 are radiated by the individual secondantennas 221 towards the target object 3. The target object 3 reflectsthe signal portions 11, 12, 16, 17 of the first and second transmitradar signal 10, 15 at least partly back to the antenna device 200.

At the antenna device 200, the first signal portions 11, 16, whichoccupy the first frequency band, are transduced by two separated firstantennas 211 and the second signal portions 12, 17, which occupy thesecond frequency band, are transduced by two separated second antennas221. The first antennas 211 are resonant in the first frequency band ofthe first signal portions 11, 16 and they are off-resonant in the secondfrequency band of the second signal portions 12, 17. Analogously, thesecond antennas 221 are resonant in the second frequency band of thesecond signal portions 12, 17 and they are off-resonant in the firstfrequency band of the first signal portions 11, 16.

One of the first antennas 211 and one of the second antennas 221 arecoupled via a first common receive signal port 135 to a first receivechain 127 of a signal receiver 110 of the radar circuit 100. Likewise,the other one of the first antennas 211 and the other one of the secondantennas 221 are coupled via a second common receive signal port 136 toa second receive chain 128 of the signal receiver 110.

The antenna device 200 routes a first signal portion 21 of a firstreceive radar signal 20 from the first antenna 211 that is coupled tothe first common receive signal port 135 and a second signal portion 22of the first receive radar signal 20 from the second antenna 221 that iscoupled to the first common receive signal port 135 via the first commonreceive signal port 135 to the first receive chain 127. The antennadevice 200 further routes a first signal portion 26 of a second receiveradar signal 25 from the first antenna 211 that is coupled to the secondcommon receive signal port 136 and a second signal portion 27 of thesecond receive radar signal 25 from the second antenna 221 that iscoupled to the second receive signal port 136 via the second commonreceive signal port 136 to the second receive chain 128. The individualfirst signal portions 21, 26 constitute first antenna signals that aretransduced by the first receive antennas 211 and the individual secondsignal portions 22, 27 constitute second antenna signals that aretransduced by the second receive antennas 221.

The first signal portion 21 of the first receive radar signal 20comprises the fractions of the first signal portions 11, 16 of the firstand second transmit radar signals 10, 15 that are received by the firstantenna 211 coupled to the first common receive signal port 135. Thesecond signal portion 22 of the first receive radar signal 20 comprisesthe fractions of the second signal portions 12, 17 of the first andsecond transmit radar signals 10, 15 that are received by the secondantenna 221 coupled to the first common receive signal port 135.

Likewise, the first signal portion 26 of the second receive radar signal25 comprises the fractions of the first signal portions 11, 16 of thefirst and second transmit radar signals 10, 15 that are received by thefirst antenna 211 coupled to the second common receive signal port 136.The second signal portion 27 of the second receive radar signal 25comprises the fractions of the second signal portions 12, 17 of thefirst and second transmit radar signals 10, 15 that are received by thesecond antenna 221 coupled to the second common receive signal port 136.

The first receive chain 127 generates a first radar data signal 123 thatrepresents the first radar signal 20 received from the first commonreceive signal port 135 and the second receive chain 128 generates asecond radar data signal 124 that represents the second radar signal 25received from the second common receive signal port 136. The signalreceiver 110 is connected to the signal processing device 120 and thefirst and second radar data signal 123, 124 are transferred from thesignal receiver 110 to the signal processing device 120.

The first transmit chain 125 and the second transmit chain 126 generatethe respective first portions 11, 16 of the first transmit radar signal10 and the second transmit radar signal 15 having different values of afirst separability parameter and they generate the respective secondportions 12, 17 of the first transmit radar signal 10 and the secondtransmit radar signal 15 having different values of a secondseparability parameter. Using the first separability parameter, thesignal processing device 120 is able to separate the parts of the firstsignal portions 21, 26 of the first and second receive radar signal 20,25 that originate from the first portion 11 of the first transmit radarsignal 10 from the parts of the first signal portions 21, 26 of thefirst and second receive radar signal 20, 25 that originate from thefirst portion 16 of the second transmit radar signal 15. Likewise, thesignal processing device 120 uses the second separability parameter toseparate the parts of the second signal portions 22, 27 of the first andsecond receive radar signal 20, 25 that originate from the secondportion 12 of the first transmit radar signal 10 from the parts of thesecond signal portions 22, 27 that originate from the second portion 17of the second transmit radar signal 15.

Additionally, the signal processing device 120 separates the firstsignal portion 21 and the second signal portion 22 of the first receiveradar signal 20 using the separate frequency bands of the first andsecond signal portions 21, 22 received via the first common receivesignal port 135 and the signal processing device 120 separates the firstsignal portion 26 and the second signal portion 27 of the second receiveradar signal 25 using the separate frequency bands of the first andsecond signal portions 25, 26 received via the second common receivesignal port 136.

The first antennas 211 transduce electromagnetic radiation with a firstpolarization and the second antennas 221 transduce electromagneticradiation with a second polarization that is orthogonal to the firstpolarization. For example, the first antennas 211 may transduceelectromagnetic radiation with horizontal linear polarization and thesecond antennas 221 may transduce electromagnetic radiation withvertical linear polarization, or vice versa.

The radar device 1 establishes a total of eight different propagationchannels from the antenna device 200 to the target object 3 and back tothe antenna device 200 and the signal processing device 120 isconfigured to separately detect the target reflections propagating viathe individual propagation channels to establish a virtual antenna arrayin a MIMO configuration. Among the eight different propagation channels,a first set of four propagation channels is operating in the firstfrequency band and a second set of four propagation channels isoperating in the second frequency band.

The radar device 1 establishes a first propagation channel 70 from thefirst antenna 211 coupled to the first common transmit signal port 130to the first antenna 211 coupled to the first common receive signal port135, a second propagation channel 71 from the second antenna 221 coupledto the first common transmit signal port 130 to the second antenna 221coupled to the first common receive signal port 135, a third propagationchannel 72 from the first antenna 211 coupled to the first commontransmit signal port 130 to the first antenna 211 coupled to the secondcommon receive signal port 136, and a fourth propagation 73 channel fromthe second antenna 221 coupled to the first common transmit signal port130 to the second antenna 221 coupled to the second common receivesignal port 136.

The radar device 1 further establishes a fifth propagation channel 74from the first antenna 211 coupled to the second common transmit signalport 131 to the first antenna 211 coupled to the first common receivesignal port 135, a sixth propagation channel 75 from the second antenna221 coupled to the second common transmit signal port 131 to the secondantenna 221 coupled to the first common receive signal port 135, aseventh propagation channel 76 from the first antenna 211 coupled to thesecond common transmit signal port 131 to the first antenna 211 coupledto the second common receive signal port 136, and an eight propagationchannel 77 from the second antenna 221 coupled to the second commontransmit signal port 131 to the second antenna 221 coupled to the secondcommon receive signal port 136.

The first set of propagation channels is established by the first signalportions transduced via the first antennas 211. It comprises the firstpropagation channel 70, the third propagation channel 72, the fifthpropagation channel 74 and the seventh propagation channel 76. Thesecond set of propagation channels is established by the second signalportions transduced via the second antennas 221. It comprises the secondpropagation channel 71, the fourth propagation channel 73, the sixthpropagation channel 75 and the eighth propagation channel 77.

With the radar device 1 shown in FIG. 1, the individual antennas 211,221 may each comprise a single antenna element or several antennaelements. The antenna elements forming a single antenna 211, 221 arethen all connected to a single common signal port 130, 131, 135, 136 ofthe radar circuit 100. Each common signal port 130, 131, 135, 136 isconnected to at least a first antenna element that is part of one of thefirst antennas 211 and a second antenna element that is part of one ofthe second antennas 221.

Each antenna 211, 221 is connected via a single signal port 130, 131,135, 136 to the radar circuit 100. The individual signal portions 11,12, 16, 17, 21, 22, 26, 27 of the radar signals 10, 15, 20, 25 thenconstitute individual antenna signals, each antenna signal beingtransduced by a separate antenna 211, 221.

Alternative embodiments of the radar device 1 shown in FIG. 1 maycomprise more than two transmit chains 125, 126 and common transmitsignal ports 130, 131, for example three transmit chains and threeassociated transmit signal ports, as well as more than two receivechains 127, 128 and common receive signal ports 135, 136, for examplefour receive chains and four associated receive signal ports. To eachsignal port, a first antenna and a second antenna may be coupled and theindividual radar signals routed via the individual signal ports may eachcomprise a first signal portion occupying the first frequency band and asecond frequency portion occupying the second frequency band. Theantenna device may then be configured to transduce the individual firstsignal portions as first antenna signals via the first antennas and theindividual second signal portions as second antenna signals via thesecond antennas. The individual first signal portions may differ amongeach other at least in a first separability parameter and the individualsecond signal portions may differ among each other at least in thesecond separability parameter.

FIG. 2 shows a first transmission 51 of the first antennas 211 versusfrequency 30 and a second transmission 52 of the second antennas 221versus frequency 30. The first transmission 51 exceeds a minimumtransmission 42 in the first frequency band 31 between a first minimumfrequency 32 and a first maximum frequency 33 and the secondtransmission 52 exceeds the minimum transmission 42 in the secondfrequency band 34 between a second minimum frequency 35 and a secondmaximum frequency 36.

The first minimum frequency 32 may amount to 75.5 GHz and the secondmaximum frequency 36 may amount to 81.5 GHz. The first maximum frequency33 may amount to 77.5 GHz and the second minimum frequency 35 may amountto 79.5 GHz.

As can be seen from FIG. 2, the first frequency band 31 and the secondfrequency band 34 are separated from each other and do not overlap. Thefirst signal portions 11, 16, 21, 26 of the radar signals 10, 15, 20, 25processed by the radar circuit 100 of the radar device 1 shown in FIG. 1occupy the first frequency band 31 and the second signal portions 12,17, 22, 27 of the radar signals 10, 15, 20, 25 occupy the secondfrequency band 34. In alternative embodiments of the radar device 1, thefrequency bands 31, 34 may alternatively be defined by two separateminimum transmissions that differ from each other.

FIG. 3 shows the frequency 30 of the first radar signal 10 and thesecond radar signal 15 generated by the signal generator 105 of theradar device 1 shown in FIG. 1 over time 60. The frequency 30 of theradar signals 10, 15 is repeatedly cycled through the second frequencyband 34 and the first frequency band 31. In the exemplary embodimentshown in FIG. 3, the frequency 30 of the radar signals 10, 15 is firstlinearly swept in the second frequency band 34 from the second maximumfrequency 36 to the second minimum frequency 35 and is then linearlyswept in the first frequency band 31 from the first maximum frequency 33to the first minimum frequency 32. Subsequently, this cycle or burst isrepeated. The frequency 30 of the first and second radar signals 20, 25measured by the signal receiver 110 has the same time-dependence as theradar signals 10, 15 shown in FIG. 3. Between the second frequency band34 of the first signal portions 11, 16, 21, 26 and the first frequencyband 31 of the second signal portions 12, 17, 22, 27, a frequency gap islocated that spans the frequencies between the second minimum frequency35 and the first maximum frequency 33.

In alternative embodiments, a different frequency sweep may be employedwithin the first frequency band 31 and/or within the second frequencyband 34. For example, the frequency 30 may be swept from lowerfrequencies to higher frequencies. The frequency sweep may also startwith a sweep over the first frequency band 31 instead of starting withthe sweep over the second frequency band 34.

FIG. 4 shows a second embodiment of the radar device 1 according to thepresent disclosure. As far as no differences are apparent from thedescription and the drawings, the radar device 1 of the secondembodiment is configured as it is described and shown in connection withthe radar device 1 according to the first embodiment shown in FIG. 1 andvice versa.

Besides the first common transmit signal port 130 and the second commontransmit signal port 131 shown in FIG. 1, the radar circuit 100 maycomprise further common transmit signal ports, for example one furthercommon transmit signal port 133, as shown in FIG. 4. Analogously, theradar circuit 100 may comprise further common receive signal ports, forexample two further common receive signal ports 137, as shown in FIG. 4.

Each common signal port 130, 131, 133, 135, 136, 137 is coupled via acommon signal line 205 to an individual signal routing device 230. Eachsignal routing device 230 has a first port 231 and a second port 232.Each first port 231 is coupled to an individual first antenna 211transducing in the first frequency band 31 and each second port 232 iscoupled to an individual second antenna 221 transducing in the secondfrequency band 34. The first antennas 211 each comprise a set ofserially coupled first antenna elements 213 and the second antennas 221each comprise a set of serially coupled second antenna elements 223.

The signal generator 105 is controlled to generate individual radarsignals for every common transmit signal port 130, 131, 133, each radarsignal having a first signal portion occupying the first frequency band31 and a second signal portion occupying the second frequency band 34.The individual first signal portions all differ in a first separabilityparameter and the individual second signal portions all differ in asecond separability parameter.

The signal processing device 120 of the radar device 1 shown in FIG. 4is configured to evaluate a total of twenty-four propagation channelscomprising a first set of twelve propagation channels operating in thefirst frequency band 31 and a second set of twelve propagation channelsoperating in the second frequency band 34. The propagation channels ofthe first set comprise all pairs of one of the first antennas 211coupled to the common transmit signal ports 130, 131, 133 and one of thefirst antennas 211 coupled to the common receive signal ports 135, 136,137. The propagation channels of the second set comprise all pairs ofone of the second antennas 221 coupled to the common transmit signalports 130, 131, 133 and one of the second antennas 221 coupled to thecommon receive signal ports 135, 136, 137.

The signal routing device 230 may be configured as a frequency selectivedevice. FIG. 5 shows an exemplary embodiment of such a frequencyselective signal routing device 230. The common signal line 205 isdirectly and in parallel coupled to a first transmission line segment236 and a second transmission line segment 237 of a frequency selectivesection 235 of the signal routing device 230. The first line segment 236is coupled via a first filter 238 of the frequency selective section 235to the first port 231 and the second line segment 237 is coupled via asecond filter 239 of the frequency selective section 235 to the secondport 232.

The first line segment 236 has an electric length of 0° and the secondline segment 237 has an electric length of 170°, both at a centerfrequency that is located between the first minimum frequency 32 and thesecond maximum frequency 36. The first filter 238 and the second filter239 are configured as bandpass filters, the first filter 238 having acenter frequency that corresponds to the center frequency of the firstfrequency band 31 and the second filter 239 having a center frequencythat corresponds to the center frequency of the second frequency band34.

The signal routing device 230 may also be configured as a switchingdevice like it is shown in an exemplary embodiment in FIG. 6. Theswitching device 23 is connected via a control line 102 to the signalprocessing device 120 and receives a switch control signal from thesignal processing device 120 via the control line 102. Depending on thestate of the switch control signal, the signal switching device 230conductively couples the first signal port 231 or the second signal port232 to the common signal line 205. The signal processing device 120 isconfigured to change the state of the switch control signalsimultaneously with the control signals 121, 122 determining thefrequency of the transmit radar signals 10, 15 generated by the signalgenerator 105 of the radar circuit 100 so that the first port 231 isconductively coupled to the common signal line 205 when the firstportions 11, 16 of the transmit radar signals 10, 15 are routed betweenthe antenna device 200 and the radar circuit 100 and that the secondport 232 is conductively coupled to the common signal line 205 when thesecond portions 12, 17 of the transmit radar signals 10, 15 are routedbetween the antenna device 200 and the radar circuit 100.

In alternative embodiment, the switching device 23 may be configured toroute signals from both the first and second frequency band 31, 34 viaboth first and second port 231, 232. In this case, the first and secondsignal portions 11, 12, 16, 17, 21, 22, 26, 27 of the radar signals 10,15, 20, 25 may span both frequency bands 31, 34. The antenna device 200may then alternately transduce either the first signal portions 11, 16,21, 26 or the second signal portions 12, 17, 22, 27 in a timemultiplexed manner.

FIG. 7 shows another embodiment of the signal routing device 230.According to this embodiment, the signal routing device 230 comprises aplurality of filters that are directly coupled between the common signalline 205 and the individual antennas coupled to the common signal line205. The plurality of filters comprises a first filter 281 and a secondfilter 282. The first filter 281 is coupled between the first signalport 231 leading to antenna elements 213 of the first antenna 211 andthe common signal line 205 and the second filter is coupled between thesecond signal port 232 leading to antenna elements 223 of the secondantenna 221 and the common signal line 205.

The first filter 281 configured to pass the first signal portion 11, 16,21, 26 and to block the second signal portion 12, 17, 22, 27 of theradar signal 10, 15, 20, 25. The second filter 282 is configured to passat least the second signal portion 12, 17, 22, 27. It may additionallybe configured to block the first signal portion 11, 16, 21, 26.

As can be seen from FIG. 7, the signal routing device 230 according tothe present disclosure may generally comprise additional signal portsthat couple additional antennas or antenna elements of additionalantennas to the common signal line and to the common signal port 130,131, 135, 136 of the radar circuit 100. The signal routing device 213may then comprise additional filters that only pass one of theadditional signal portions of the radar signal and block all othersignal portions of the radar signal. For example, the signal routingdevice 230 may comprise a third port 233 that is coupled to antennaelements 228 of a third antenna 229. The third port 233 is coupled via athird filter 283 to the common signal line 205. The third filter 283 isconfigured to pass a third signal portion of the radar signal 10, 15,20, 25 that occupies a third frequency band and to block the firstsignal portion 11, 16, 21, 26 and/or the second signal portion 12, 17,22, 27 of the radar signal. Likewise, the antenna elements of the thirdantenna 229 are configured to transduce the third signal portion.

Analogously to the signal routing device 230 shown in FIG. 7, also thesignal routing devices 230 shown in FIGS. 5 and 6 may be coupled betweenmore than two antennas or antenna elements of more than two antennas andthe common signal line 205. These signal routing devices 230 may routeindividual signal portions occupying separate frequency bands to theindividual antennas coupled to their signal ports. In general, signalrouting devices 230 having separate filters coupled between individualantennas or antenna elements of individual antennas and the commonsignal line 205 may be used instead of the multiplexers or diplexersdescribed in the present disclosure.

FIG. 8 shows a first antenna 211 and a second antenna 221 that are bothinductively coupled to a common signal line 205 and a common signal port204 and that may be used with the antenna devices 200 according to thepresent disclosure. Inductive coupling between the antennas 211, 221 andthe common signal line 205 is achieved by placing the antennas 211, 221or individual antenna elements of the antennas 211, 221 in the proximityof the common signal line 205 so that the electromagnetic fieldgenerated by the signal line 205 couples to the antennas 211, 221. Inalternative embodiments, one of the first and second antennas 211, 221may be conductively coupled to the common signal line 205 and the otherone of the antennas 211, 221 may be inductively coupled to the signalline 205 or to the antenna 211, 221 that is conductively coupled to thesignal line 205.

FIG. 9 shows an alternative embodiment of a first antenna 211 and asecond antenna 221 that are coupled via a common signal line 205 to acommon signal port 204 and that may be used with the antenna devices 200according to the present disclosure. In this embodiment, the firstantenna 211 and the second antenna 221 are serially coupled to thecommon signal line 205 and a filter element 285 is placed between thefirst antenna 211 and the second antenna 221. The filter element 285 isconfigured to block the first signal portion of the radar signaltransduced via the common signal port 204 and to pass the second signalportion of the radar signal to the second antenna 221.

As it is shown in FIG. 9, further antennas 229 may be coupled to thecommon signal line 205 behind the second antenna 221. The individualfurther antennas 229 may each transduce a separate signal portion of theradar signal. In this case, the filter element 285 passes all signalportions but the first signal portion radiated by the first antenna 211.Additionally, each further antenna 229 is coupled via a further filterelement 286 to the preceding antennas 211, 221, 229. The individualfurther filter elements 286 each pass all signal portions radiated bythe further antennas 229 that are coupled to the common signal line 205behind the respective further filter element 286 and block all signalportions of the radar signal that are radiated by the antennas 211, 221,229 coupled to the common signal line 205 in front of the respectivefurther filter element 286. Each antenna shown in FIG. 9 may compriseseveral antenna elements coupled to each other.

FIG. 10 shows an implementation of the serial coupling of the firstantenna 211 and the second antenna 221 shown in FIG. 9 using arrayantennas that are configured as slotted waveguide antennas. The radarsignal 10 propagates from the common signal line 205 via the waveguideof the first antenna 211 to the filter element 285, where the firstsignal portion 11 of the radar signal 10 is blocked and the secondsignal portion 12 is passed into the waveguide of the second antenna221. With the antenna device shown in FIG. 10, the first antenna 211 maybe configured to only transduce the first signal portion 11 and thesecond antenna 221 may be configured to only transduce the second signalportion 12.

FIG. 11 shows a third embodiment of the radar device 1. As long as nodifferences are apparent from the description or the figures, the thirdembodiment of the radar device 1 is configured as it is described forthe second embodiment and vice versa.

The third embodiment of the radar device 1 does not comprise the signalrouting devices 230 of the second embodiment. Instead, the firstantennas 211 and the second antennas 221 are serially coupled to thecommon signal lines 205. The first antennas 211 are only resonant withinthe first frequency band 31 and therefore only transduce the firstsignal portions of the radar signals and the second antennas 221 areonly resonant within the second frequency band 34 and therefore onlytransduce the second signal portions of the radar signals. The firstantennas 211 are configured as array antennas that comprise leakytraveling waveguide antenna elements and the second antennas 221 areconfigured as array antennas that comprise series-fed antenna elements.

FIG. 12 shows an exemplary placement of the antennas 211, 221 of thethird embodiment of the radar device 1 on a front surface of the antennadevice 200. The antennas 211, 221 of the second embodiment of the radardevice 1 may be placed in an analogous way, as it is shown in FIG. 13.

The first antennas 211 form a first set 210 of antennas that arearranged in a first MIMO array along a first direction 201 and thesecond antennas 221 form a second set 220 of antennas that are arrangedin a second MIMO array along a second direction 202 that isperpendicular to the first direction 201. The second antennas 221 aredisplaced with respect to each other along the second direction 202.Although not shown in FIGS. 12 and 13, the first antennas 211 aredisplaced with respect to each other along the first direction 201analogously to the displacement of the second antennas 221 along thesecond direction 202.

The second transmit antennas 221 that are coupled to the common transmitports 130, 131, 133 have a first transmit distance 271 between a firstone and a second one of the second receive antennas 221 and a secondtransmit distance 272 between the second one and a third one of thesecond transmit antennas 221. The first transmit distance 271 may, forexample, amount to half a wavelength at a selected frequency and thesecond transmit distance 272 may amount to the wavelength at theselected frequency. The selected frequency may lie within the secondfrequency band 34 and may amount to the center frequency of the secondfrequency band 34, for example.

The second receive antennas 221 that are coupled to the common receiveports 135, 136, 137 have a first receive distance 273 between a firstone and a second one of the second receive antennas 221, a secondreceive distance 274 between the second one and a third one of thesecond receive antennas 221, and a third receive distance 275 betweenthe third one and a fourth one of the second receive antennas 221. Thefirst receive distance 273 may amount to 0.7-times the wavelength at theselected frequency, the second receive distance 274 to 1.5-times thewavelength at the selected frequency and the third receive distance 275to 3.5-times the wavelength at the selected frequency.

The signal processing device 120 of the radar device 1 is configured toconstruct from the first antenna signals transduced via the firstantennas 211 a first virtual antenna array that extends along the firstdirection 201 and that resolves targets along the first direction 201and to construct from the second antenna signals transduced via thesecond antennas 221 a second virtual antenna array that extends alongthe second direction 202 and resolves targets along the second direction202. The first and second antenna array each are configured as MIMOarrays.

Although shown in connection with the third embodiment of the radardevice 1, the antenna arrangement of FIG. 12 that forms a first virtualarray along the first direction 201 and a second virtual array along thesecond direction 202 may also be realized with the second embodiment ofthe radar device 1 that employs the signal routing devices 230 and isshown schematically in FIG. 4. The corresponding arrangement of theantennas 211, 221 of the second embodiment of the radar device 1 isshown in FIG. 13. As far as no differences are apparent from thedescription and the drawings, the antenna placement shown in FIG. 13 isconfigured as it is described and shown in connection with the antennaplacement shown in FIG. 12 and vice versa.

With the antenna devices 200 of the preceding Figures, the firstantennas 211 and the second antennas 221 that are coupled to a commonsignal port 130, 131, 133, 135, 136, 137 of the radar circuit 100 areconfigured as separate antennas that are positioned at differentlocations of the antenna device 200 and consequently transduce radiationfields that have phase centers that are shifted with respect to eachother. In alternative embodiments, first antennas 211 and secondantennas 221 that are coupled to a common signal port 130, 131, 133,135, 136, 137 may also coincide and be located at the same position onthe antenna device 200, as it is exemplarily shown in FIG. 14 inconnection with a fourth embodiment of the radar device 1 according tothe present disclosure.

As far as no differences are apparent from the description and thedrawings, the radar device 1 of the fourth embodiment is configured asit is described and shown in connection with the radar device 1according to the third embodiment shown in FIG. 11 and vice versa.

In the fourth embodiment of the radar device, 1, the individual firstand second antennas 211, 221 that are together coupled to a commonsignal port 130, 131, 133, 135, 136, 137, 137 are colocated and thecorresponding first and second antenna elements 213, 223 coincide. Theresulting common antennas 218 are configured as dual-polarized antennasthat transduce radiation in the first frequency band 31 with a firstpolarization and that transduce radiation in the second frequency band34 with a second polarization. The second polarization may be orthogonalto the first polarization. The first polarization may be linearpolarization along a first polarization direction 206 and the secondpolarization may be linear polarization along a second polarizationdirection 207 that is perpendicular to the first polarization direction206.

With the common antennas 218 shown in FIG. 14, separate phase centers ofthe first and second antennas 211, 221 coupled to a common signal port130, 131, 133, 135, 136, 137 are realized by generating thecorresponding first and second antenna signals having differentfrequencies and by configuring the common antennas 218 as series fedarray antennas. The different frequencies of the first and secondantenna signals then result in the individual antenna elements 213, 223of the series fed array antennas 218 transducing first and secondantenna signal with different amplitudes and phases. This, in turn alsoresults in the first and second antennas 211, 221 of the common antennas218 having shifted phase centers with respect to each other.

In other alternative embodiments of the radar devices 1 of the presentdisclosure, the first antennas 211 and the second antennas 221 may beshaped and/or positioned to have fields of view with different extendsalong a lateral direction. As it is shown in FIG. 15, the first antennas211 may be positioned to have a first field of view 240 and the secondantennas 221 may be positioned to have a second field of view 242. Thefirst field of view 240 has a first extent 241 along the lateraldirection 203, which is larger than a second extent 243 of the secondfield of view 242 along the lateral direction 203. The lateral direction203 may be, for example, the first direction 201 or the second direction202 shown in FIGS. 12 to 14.

A first propagation channel 70 between the radar device 1 and a targetobject 3 that is located inside the first field of view 240 and outsidethe second field of view 242 comprises a signal path that is establishedby the first antennas 211 of the radar device 1. Likewise, a secondpropagation channel 71 between the radar device 1 and a further targetobject 4 that is located inside the second field of view 242 and outsidethe first field of view 240 comprises a signal path that is establishedby the second antennas 221 of the radar device 1. The signal processingdevice 120 is configured to detect reflections from the target object 3that are received via the first propagation channel 70 using andanalyzing the first signal portions 11, 16, 21, 26 and to detectreflections from the further target object 4 that are received via thesecond propagation channel 71 by using and analyzing the second signalportions 12, 17, 22, 27. An additional target object 5 that is locatedinside the first and second field of view 240, 242 is irradiated by boththe first antennas 211 and the second antennas 221.

FIG. 16 shows an exemplary placement of antenna elements 213, 222, 223of the first and second antennas 211, 221 that realizes the field ofviews 240, 242 shown in FIG. 15. The first transmit antennas 211 coupledto the common transmit signal ports 130, 131, 133 and the first receiveantennas 211 coupled to the common receive signal ports 135, 136, 137each comprise first antenna elements 213 only. At least some of thesecond transmit antennas 221 coupled to the common transmit signal ports130, 131, 133 and at least some of the second receive antennas 221coupled to the common receive signal ports 135, 136, 137, namely thesecond transmit antennas 211 and second receive antennas 221 positionedat the outer sides of the arrangements of second antenna elements 223 inthe lateral direction 203, comprise second antenna elements 223 as wellas additional antenna elements 222. The additional antenna elements 222are placed at the outer sides of the second antenna elements 223 in thelateral direction 203.

The additional antenna elements 222 may be passive elements that have noconductive coupling to the common signal ports 130, 131, 133, 135, 136,137 of the radar circuit 100. Alternatively, they may be active elementsthat actively transduce radar signals that are routed via the commonsignal ports 130, 131, 133, 135, 136, 137. For example, the additionalantenna elements 222 may be serially coupled to the second antennas 221located at the outer positions of the second antennas 221 and maytransduce in the second frequency band 34 only. Alternative embodimentsof the first and second antennas 211, 221 shown in FIG. 16 may featureadditional antenna elements 222 positioned at the sides of all secondantennas 223.

FIG. 17 shows another exemplary placement of the antenna elements 213,223 of first and second antennas 211, 221 that realizes the fields ofview shown in FIG. 15. The first antenna 211 has two sets of seriallycoupled first radiating elements 213 that are coupled in parallel to thefirst signal port 131 of the signal routing device 230. Likewise, thesecond antenna 221 has two sets of serially coupled second radiatingelements 223 that are coupled in parallel to the second signal port 132of the signal routing device 230. The sets of serially coupled firstradiating elements 213 are placed next to each other in the lateraldirection 203 and the two sets of serially coupled second radiatingelements 223 are placed on both sides of the sets of first radiatingelements 213 in the lateral direction 203.

In addition to the second antenna elements 223, the second antenna 221also comprises the first antenna elements 213 and the first antennaelements 213 are configured to transduce both in the first frequencyband 31 and in the second frequency band 34. The signal routing device230 is configured to route the first signal portion 11 of the radarsignal 10 only between the first antenna elements 213 and the commonsignal port 130 and to route the second signal portion 221 of the radarsignal 10 between the common signal port 130 and both the second antennaelements 223 and the first antenna elements 213. Consequently, theantenna device 200 transduces radar signals in the first frequency band31 only via the first radiating elements 213 and it transduces radarsignals in the second frequency band 34 via both the first radiatingelements 213 and the second radiating elements 223.

The first radiating elements 213 and the second radiating elements 223are arranged in a way that the first radiating elements 213 form a firstantenna array and that the second radiating elements 223 together withthe first radiating elements 213 form a second antenna array with anarrower beam solid angle than the first antenna array. The firstantenna array and/or the second antenna array may be configured asphased arrays.

In all embodiments of the radar device 1 according to the presentdisclosure, further antennas may be coupled to the individual commonsignal ports 130, 131, 133, 135, 135, 136, 137 besides the firstantennas 211 and the second antennas 221. The antenna device 200 maythen transduce electromagnetic radiation via the individual antennas inmutually separate frequency bands so that mutually separate signalportions of the radar signals routed via the common signal ports 130,131, 133, 135, 135, 136, 137 may each be transduced via a specificindividual antenna coupled to the respective signal port 130, 131, 133,135, 135, 136, 137. For example, the signal routing devices 230 shown inFIGS. 4, 5, 6, 7 and 13 and 17 all may have an additional port for eachfurther antenna coupled to the respective common signal port 130, 131,133, 135, 135, 136, 137. Also, more than two antennas 211, 221 may beproximity coupled to the common signal line 205 shown in FIG. 8 and morethan two antennas 211, 221 may be serially coupled to the common signallines 205 shown in FIGS. 10, 11, 12 and 16.

The radar devices 1 described in connection with the previous Figuresare configured as distance sensing radar devices that employ frequencymodulated continuous wave radar signals, for example the frequencymodulated radar signals 10, 15 shown in FIGS. 2 and 3. The signalprocessing devices 120 of the radar devices 1 are configured to jointlyprocess the first and second radar signals 10, 15, 20, 25 and to useboth the first and second frequency band 31, 34 to determine thedistance to target objects that are located within a common field ofview 240, 242 of both the first and second antennas 211, 221, such asthe additional target object 5 shown in FIG. 15.

FIG. 18 schematically shows a signal processing device 120 that may beused with the radar devices 1 of the present disclosure and the radarsignals 10, 20 shown in FIG. 3. The signal processing device 120 isconfigured to jointly process the signal portions 11, 12 of the firsttransmit radar signal 10 that are transduced via transmit antennas 211,221 coupled to a first common transmit signal port 130 together with thesignal portions 21, 22 of the first receive radar signal 20 that aretransduced via receive antennas 211, 221 coupled to a first commonreceive signal port 135. After receiving the first receive radar signal20 containing the first signal portion 21 and the second signal portion22 via the first common receive signal port 135, a first receive chain127 generates a first radar data signal 123 representing the first andsecond signal portion 21, 22.

The first radar data signal 123 is received by a splitting module 140that is configured to separate the portion of the first radar datasignal 123 that represents the first signal portion 21 from the portionthat represents the second signal portion 22. The data representing thefirst signal portion 21 is evaluated by a first evaluation module 144 toevaluate reflection via a first propagation channel 70 shown in FIG. 1and the data representing the second signal portion 22 is evaluated by asecond evaluation module 145 that evaluates reflection via the thirdpropagation channel 72 shown in FIG. 1. Additionally, the splittingmodel 140 routes all data corresponding to the first and second signalportions 21, 22 received from the receive chain 127 to a ranging module142. The ranging module 142 is configured to jointly process the datafrom the first and second signal portions 21, 22 to determine thedistance to the target object 5 irradiated by the antenna device 200.

For determining the distance to the target object 5 from the signalportions 21, 22 of the receive radar signal 20, the ranging module 142is configured to determine a phase shift of the receive radar signal 20that is transduced via the receive antennas 211, 221 with respect to thetransmit radar signal 10 that is transduced via the transmit antennas211, 221. To this end, the ranging module 142 comprises a mixing module151 that mixes the transmit radar signal 10 containing the first andsecond signal portion 11, 12 with the receive radar signal 20 containingthe first and second signal portions 21, 22 to generate an intermediatesignal 152 at an intermediate frequency that equals the instantaneousfrequency difference between the first receive radar signal 20 and thefirst transmit radar signal 10. The radar circuit may employ the linearfrequency sweeps shown in FIG. 3, in which case the intermediatefrequency is constant over time.

The frequency of the intermediate signal 152 is a measure for the phaseshift that the first radar signal acquires upon reflection at the targetobject. To determine the distance of the target object, the rangingmodule 142 comprises a measurement module 154 that measures theintermediate frequency and determines the target distance from themeasured intermediate frequency. For measuring the target distance, themeasurement module 154 may perform a Fourier transform, for example afast Fourier transform (FFT), on the intermediate signal 152. Since theminimum resolvable frequency difference is given by the bandwidth of theintermediate signal 152 and thus the bandwidth of the signals used togenerate the intermediate signal 152, jointly processing the first andsecond signal portions 21, 22 increases the resolution of the rangingmodule 142 compared to a single evaluation of only the first or secondsignal portion 21, 22.

With the signal processing device 120 shown in FIG. 18, the splittingmodule 140, the evaluation modules 144, 145, the ranging module 142, themixing module 151 and/or the measurement module 154 may be realized bysoftware modules or software functions implemented on one or severallogic units of the signal processing device 120. The individual modulesthen process the data signals 121, 123 representing the radar signals10, 20. Alternatively, the splitting module 140, the mixing module 151,the evaluation modules 144, 145, the ranging module 142 and/or themeasurement module 154 may be integrated in the receive chain 127. Thesemodules may then be configured to directly process all signal portions21, 22 of the radar signal 20 at the radar frequencies.

With all radar devices 1 of the present disclosure, the first antennas211 may have the first transmission 51 and the second antennas 221 havethe second transmission 52 shown in FIG. 2. The radar signals routed viathe common signal ports 130, 131, 133, 135, 136, 37 may then vary infrequency 30 over time 60 as shown in FIG. 3. However, since thefrequency sweep within the first and second frequency bands 31, 34 doesnot cover the entire bandwidth between the first minimum frequency 32and the second maximum frequency 36, the radar devices 1 cannot use theentire bandwidth between the first minimum frequency 32 and the secondmaximum frequency 36 for distance sensing applications.

In alternative embodiments of the radar devices 1 according to thepresent disclosure, the first transmission 51 of the first antennas 211and the second transmission 52 of the second antennas 221 are configuredas shown in FIG. 19. In the first frequency band 31, only the firsttransmission 51 is larger than the minimum transmission 42, while in thesecond frequency band 34, only the second transmission 52 is larger thanthe minimum transmission 42. In a third frequency band 37, which islocated in between the first frequency band 31 and the second frequencyband 34, both the first transmission 51 and the second transmission 52are larger than the minimum transmission 42.

Therefore, only the first antennas 211 and not the second antennas 221transduce in the first frequency band 31, while in the second frequencyband 34 only the second antennas 221 and not the first antennas 211transduce. In the third frequency band 37, the first transmissions 51 ofthe first antennas 211 and the second transmissions 52 of the secondantennas 221 overlap and both the first antennas 211 and the secondantennas 221 transduce in the third frequency band 37.

The first, second and third frequency bands 31, 34, 37 directly joinwith each other so that the first maximum frequency 33 equals a thirdminimum frequency 38 of the third frequency band 37 and the secondminimum frequency 35 equals a third maximum frequency 39 of the thirdfrequency band 37. With the transmissions 51, 52 shown in FIG. 19, theantenna device 1 continuously transduces over the combined frequencyband between the first minimum frequency 32 of the first frequency band31 and the second maximum frequency 34 of the second frequency band 34.

FIG. 20 shows individual bursts of a radar signal 10 routed via thecommon signal port to or from the first and second antennas 211, 221having the transmissions 51, 52 shown in FIG. 19. The radar signal 10comprises continuous linear frequency sweeps from the second maximumfrequency 34 down to the first minimum frequency 32. These frequencysweeps span the first signal portion 11 occupying the first frequencyband 31, a third signal portion 13 occupying the third frequency band 37and the second signal portion 12 occupying the second frequency band 34.The frequency sweeps all have the same slope within the individualfrequency bands 31, 34, 37. Target objects that are located in thecommon field of view 240, 242 of the first antennas 211 and the secondantennas 221 are irradiated with electromagnetic radiation spanning thecomplete frequency band between the first minimum frequency 32 and thesecond maximum frequency 34.

With the bursts shown in FIG. 20, the signal processing device 120 mayuse the first, second and third frequency bands 31, 34, 37 fordetermining the distance to the target object. Additionally, it may onlyuse the first signal portions 11, 16, 21, 26 of the radar signals 10,15, 20, 25 that occupy the first frequency band 31 to detect reflectionsvia the first propagation channels and it may only use the second signalportions 12, 17, 22, 27 of the radar signal 10, 15, 20, 25 that occupythe second frequency band 34 to detect reflections via the secondpropagation channels.

With the radar devices 1 of the previous Figures, the individualantennas 211, 221 are each coupled to a single signal port 130, 131,133, 135, 136, 137. The first and second signal portions 11, 12, 16, 17,21, 22, 26, 27 of the individual radar signals 10, 15, 20, 25 thenconstitute separate antenna signals representing the radiation fields ofthe individual antennas 211, 221. The antenna signals are entirelyrouted as the separate signal portions 11, 12, 16, 17, 21, 22, 26, 27over a single port 130, 131, 133, 135, 136, 137 of the radar circuit100.

The first and second antennas 211, 221 shown in FIGS. 1, 4, 7 to 13 and16 are each placed at separate locations on the antenna device 200 andtherefore have phase centers located at different positions.Consequently, these antennas 211, 221 radiate the first signal portion11, 16, 21, 26 and the second signal portion 12, 17, 22, 27 fromdifferent physical locations on the antenna device 200.

The first and second antennas 211, 221 shown in FIGS. 14 and 17 haveco-located phase centers that are positioned at the same location on theantenna device 200 and radiate the first signal portion 11, 16, 21, 26and the second signal portion 12, 17, 22, 27 from the same physicallocation. While the first and second antennas 211, 221 of the radardevice 1 shown in FIG. 14 that are coupled to the same common signalport 130, 131, 133, 135, 136, 137 comprise the same set ofdual-frequency antenna elements 213, 223, the individual first andsecond antennas 211, 221 of the radar device shown in FIG. 17 that arecoupled to the common signal port 130 have different sets of antennaelements 213, 223. The antenna elements 213, 223 are arranged togenerate co-located phase centers of the first and second antenna 211,221, whereby these phase centers are positioned at the center betweenthe two sets of serially coupled antenna elements 213 of the firstantenna 211.

The radar devices 1 where first and second antennas 211, 221 coupled toa common signal port 130, 131, 133, 135, 136, 127 have separate phasecenters may use the separate phase centers to establish differentpropagation channels and to form a virtual antenna array, such as a MIMOarray, from the individual propagation channels. For example, theprocessing unit of these radar devices 1 may use the location of firstphase centers of the first antennas 211 as first antenna positions andthe location of second phase centers of the second antennas 221 assecond antenna positions. The locations of the corresponding phasecenters thereby correspond to the phase centers of the radiationpatterns associated with the antennas 211, 221. The angular position ofa target object may then be determined by evaluating the phase shiftsthat the individual radar signals acquire when propagating via thedifferent propagation channels established by the spatially separatedantennas.

FIG. 21 illustrates a further embodiment of a radar device 1 accordingto the present disclosure that routes two antenna signals via a commonsignal port and transduces the antenna signals routed via the commonsignal port with separate phase centers. As far as no differences aredescribed or apparent from the Figures, the radar device 1 is configuredas it is disclosed in connection with the radar devices 1 shown in FIGS.1, 4, 7 to 13 and 16.

A radar circuit 100 of the radar device 1 has a first signal port 130and a second signal port 131. The first and second signal port 130, 131are each configured as common signal ports to each of which a firstantenna 211 transducing electromagnetic radiation with a first phasecenter 301 and a second antenna 221 transducing electromagneticradiation with a second phase center 302 are connected. The firstantennas 211 each transduce a first antenna signal occupying a firstfrequency band and the second antennas 221 each transduce a secondantenna signal occupying a second frequency band.

The first phase centers 301 of the first antennas 211 connected to thefirst and second common signal port 130, 131 are shifted with respect toeach other by a first distance 305 along a first direction 201 and arepositioned at the same location in a second direction 202 that isperpendicular to the first direction 201. Consequently, from the firstantenna signals transduced via the first antennas 211, a virtual antennaarray may be constructed that resolves the angular position of a targetobject along the first direction 201. The second phase centers 302 ofthe second antennas 221 connected to the first and second common signalport 130, 131 are shifted with respect to each other by a seconddistance 306 along the second direction 202 and are positioned at thesame location in the first direction 201. From the second antennasignals transduced via the second antennas 221, a virtual antenna arraymay be constructed that resolves the angular position of the targetobject along the second direction 202.

As can also be seen from FIG. 21, the phase centers 301, 302 of thefirst and second antenna 211, 221 connected to the first common signalport 130 are located at the same position in the first direction 201 andare shifted with respect to each other by the second distance 306 alongthe second direction 202. Furthermore, the phase centers 301, 302 of thefirst and second antenna 211, 221 connected to the second common signalport 131 coincide both in the first and in the second direction 201,202.

The first antennas 211 frequency selectively transduce in a firstfrequency band and the second antennas 221 frequency selectivelytransduce in a second frequency band that is separate from the firstfrequency band. The first common signal port 130 routes a first radarsignal 10 that comprises the first antenna signal as a first signalportion 11 and the second antenna signal as a second signal portion 12.Likewise, the second common signal port 131 routes a second radar signal15 that comprises the first antenna signal as a first signal portion andthe second antenna signal as a second signal portion 17. The firstsignal portions 11, 16 and first antenna signals each occupy the firstfrequency band and the second signal portions 12, 17 and second antennasignals each occupy the second frequency band.

FIG. 22 shows a further embodiment of a radar device 1. As far as nodifferences are described or apparent from the Figures, the radar device1 shown in FIG. 22 is configured as it is disclosed in connection withthe radar device 1 of FIG. 21. The radar circuit 100 of the radar deviceshown in FIG. 22 comprises a further common signal port 133 to which theadditional first and second antennas 211, 221 are connected. The firstantenna 211 connected to the further common signal port 133 has a firstphase center 301 and the second antenna 221 connected to the furthercommon signal port 133 has a second phase center 302. Both the first andsecond antenna signal are routed as individual signal portions of aradar signal via the further common signal port 133.

Like the first and second antennas 211, 221 connected to the first andsecond common signal 130, 131, the first antenna 211 connected to thefurther common signal port 133 frequency selectively transduces a firstantenna signal occupying the first frequency band and the second antenna221 connected to the further common signal port 133 frequencyselectively transduces a second antenna signal occupying the secondfrequency band.

With the radar device of FIG. 22, the first and second phase center 301,302 of the antennas 211, 221 connected to the second common signal port131 are separated from each other by the second distance 306 along thesecond direction 202 and the first and second phase centers 301, 302 ofthe antennas 211, 221 connected to the further common signal port 133are aligned with each other in the first direction 201 and separatedfrom each other along the second direction 202 by twice the seconddistance 306.

The individual first phase centers 301 of the first antennas 211connected to the individual common signal ports 130, 131, 133 arealigned with each other in the second direction 202 and separated fromeach other in the first direction 201 by the first distance 305. Thesecond phase centers 302 of the second antennas 221 connected to thefirst and second common signal port 130, 131 are separated from eachother along the second direction 202 by twice the second distance 306and the phase center 302 of the second antenna 221 connected to thefurther common signal port 133 is separated from the second phase center302 of the second antenna 221 connected to the second common signal port131 by the second distance 306.

FIG. 23 shows an alternative embodiment of the radar device 1 of FIG.22. To each of the common signal ports 130, 131, 133 three individualantennas 211, 221, 229 are connected, whereby each individual antenna211, 221, 229 transduces via a separate phase center. Therefore, eachcommon signal port 130, 131, 133 routes a first antenna signal that istransduced via a first phase center 301 of the first antenna 211, asecond antenna signal that is transduced with a second phase center 302of the second antenna 221 and a third antenna signal that is transducedwith a third phase center 303 of the third antenna 229. The individualantenna signals each occupy different frequency bands.

The individual third phase centers 303 are aligned with the first andsecond phase centers 301, 302 of the antennas 211, 221, 229 connected tothe same signal port 130, 131, 133 in the first direction 201. In thesecond direction 202, the third phase center 303 of the antenna 229connected to the first common signal port 130 is positioned at the samelocation as the second phase center 302 of the antenna 223 connected tothe third common signal port 133, the third phase center 303 of theantenna 229 connected to the second common signal port 131 is positionedat the same location as the second phase center 302 of the antenna 223connected to the first common signal port 131 and the third phase center303 of the antenna 229 connected to the third common signal port 133 ispositioned at the same location as the second phase center 302 of theantenna 223 connected to the second common signal port 132.

The antennas 229 having the third phase centers 303 realize anadditional antenna array for resolving the angular position of thetarget object in the second direction 202. The antennas 223 having thesecond phase center 302 may differ from the antennas 229 having thethird phase center 303 in at least one antenna parameter like gain,field of view, polarization or the like.

Transducing antenna signals occupying separate frequency bands withseparate phase centers is, for example, accomplished by the antennadevices 200 shown in FIGS. 1, 4, 7 to 13 and 16. All these antennadevices 200 feature individual antennas 211, 221, 229 that consist ofseparate sets of radiating elements 213, 223, 228. Alternatively,frequency selective transducement of antenna signals with separate phasecenters may also be realized with antennas that share common sets ofradiating elements, such as the antennas shown in the following FIGS. 24to 30.

FIG. 24 shows an antenna device 200 that may be used with the radardevices 1 according to the present disclosure. It has a first antenna211, a second antenna 221 and a third antenna 229 coupled to a commonsignal port 130 of a radar circuit 100. The first antenna 211 transducesin a first frequency band, the second antenna 221 transduces in a secondfrequency band and the third antenna 229 transduces in a third frequencyband. The first, second and third frequency band are separated from eachother and the second frequency band is located at higher frequenciesthan the first frequency band and the third frequency band is located inbetween the first and second frequency band. For example, the firstfrequency band may lie between 76 GHz and 77 GHz, the second frequencyband may lie between 78 GHz and 79 GHz and the third frequency band maylie between 80 GHz and 81 GHz.

The antenna device 200 comprises a first set 315 of first antennaelements 213, a second set 317 of second antenna elements 223 and athird set 318 of third antenna elements 228. In the second direction202, the second and third sets 317, 318 of antenna elements 223, 228 arearranged on opposite sides of the first antenna elements 213 of thefirst set 315. The antenna elements 213, 223, 228 are configured asindividual radiating slots provided in a waveguide, for example asurface integrated waveguide. The first antenna 211 consists of thefirst antenna elements 213 and the third antenna elements 228, thesecond antenna 221 consists of the first antenna elements 213 and thesecond antenna elements 223 and the third antenna consists of the first,second and third antenna elements 221, 223, 229.

The first antenna elements 213 of the first set 315 are directly coupledto the common signal port 130 and transduce in the first, second andthird frequency band. The second antenna elements 223 of the second set317 transduce in the second and third frequency band and the thirdantenna elements 228 of the third set 318 transduce in the first andthird frequency band. To this end, the second antenna elements 223 ofthe second set 317 are coupled to the common signal port 130 by a firstfilter 310 that is configured as a high path filter that blocks thefirst frequency band and passes the second and third frequency band,whereas the third antenna elements 228 of the third set 318 are coupledto the common signal port 130 by a second filter 311 that is configuredas a low pass filter that blocks the second frequency band and passesthe first and third frequency band. The filters 310, 311 and the commonsignal line connecting the antennas 211, 221, 229 to the common signalport 130 may be configured as surface integrated waveguide devices.

The first antenna 211 has a first phase center 301, the second antenna221 has a second phase center 302 and the third antenna 229 has a thirdphase center 303. The phase centers 301, 302, 303 are positioned at thesame location in the first direction 201 and are separated from eachother along the second direction 202. Thereby, the third phase center303 is located in between the first phase center 301 and the secondphase center 302. The antenna elements 213, 223, 228 are distributedabove each other in two rows along the second direction 202 to formarray antennas 211, 221, 229 that have a small field of view along thesecond direction 202, which may be the elevation direction with respectto a ground surface on which a vehicle comprising the radar device 1travels.

With the radar device shown in FIG. 24, the first filter 310 is locateddirectly between the second antenna elements 223 of the second set 317and the common signal port 130 and the second filter 311 is locateddirectly between the third antenna elements 228 of the third set 318 andthe common signal port 130.

FIG. 25 depicts an alternative embodiment of the antenna device 200shown in FIG. 24. With this embodiment, the first filter 310 is locatedin between the first antenna elements 213 of the first set 315 and thesecond antenna elements 223 of the second set 317, so that the secondantenna elements 223 are connected to the common signal port 130 via thefirst filter 310 and the first set 315 of first antenna elements 213.Likewise, the second filter 311 is located in between the first antennaelements 213 of the first set 315 and the third antenna elements 228 ofthe third set 318, so that the third antenna elements 228 are connectedto the common signal port 130 via the second filter 311 and the firstset 315 of first antenna elements 213.

The first filter 310 is configured as a high pass filter that onlytransduces the second frequency band and the second filter 311 isconfigured as a low pass filter that only transduces the first frequencyband. Consequently, the first antenna 211 transducing in the firstfrequency band comprises the first set 315 of first antenna elements 213and the third set 318 of third antenna elements 228, while the secondantenna 221 transducing in the second frequency band comprises the firstset 315 and the second set 317 of antenna elements 213, 223 and thethird antenna 229 transducing in the third frequency band only comprisesthe first set 315 of antenna elements 213. In alternative embodiments,the first filter 310 may be configured as a high pass filter that blocksthe first frequency band and passes the second and third frequency bandand the second filter 311 may be configured as a low pass filter thatblocks the second frequency band and passes the first and thirdfrequency band. With these embodiments, the third antenna comprises allsets 315, 317, 318 of antenna elements 213, 223, 228.

FIG. 26 shows another embodiment of an antenna device 200 for the radardevices 1 according to the present disclosure. The antenna device 200has two antennas 211, 221 that are coupled to a common signal port 130of a radar circuit 130 and transduce via separate phase centers 301,302. As far as no differences are described or apparent from thefigures, the antenna device 200 shown in FIG. 26 is configured asdisclosed in connection with the antenna device 200 shown in FIG. 24 andvice versa.

With the antenna device 200 of FIG. 26, the first set 315 of firstantenna elements 213 and the second set 317 of second antenna elements223 are positioned next to each other along the first direction 201,which is the azimuth direction. The first antenna elements 213 and thesecond antennas 223 are each distributed along two rows extending in thesecond direction 202, which is the elevation direction. The antennaelements 213, 223 are configured as individual radiating slots providedin a waveguide, for example a surface integrated waveguide, whereby thewaveguide serially connects the second antenna elements 223 via thefirst antenna elements 213 to the common signal common signal port 130of the radar circuit 100.

In between the section of the waveguide containing the first set 315 ofantenna elements 213 and the section of the waveguide containing thesecond set 317 of antenna elements 223, the waveguide has two filters310 that are configured as low pass filters that block the firstfrequency band. Consequently, the first antenna 211 transducing in thefirst frequency band comprises the first antenna elements 213 only andthe second antenna 221 transducing in the second frequency bandcomprises both the first and second antenna elements 213, 223. Thefilters 310 are located in the second direction 202 at both ends of thewaveguide section that comprises the first antenna elements 213.

The first antenna 211 then has a first phase center 301 that is locatedin the middle of the first set 315 of first antenna elements 213 and thesecond antenna 221 has a phase center that is located in between thefirst and second set 315, 317 of antenna elements 213, 223, in thecenter of the antenna structure combining the first and second antennas211, 221. The second phase center 302 is shifted with respect to thefirst phase center 301 along the first direction 201.

FIG. 27 shows another alternative embodiment of an antenna device 200for the radar devices 1 according to the present disclosure, which has afirst, second and third antenna 211, 221, 229 coupled to a common signalport 130. As far as no differences are described or apparent from theFigures, the embodiment shown in FIG. 27 is configured as it isdisclosed for the embodiment shown in FIG. 24 and vice versa.

With the embodiment shown in FIG. 27, the first set 315 of first antennaelements 213, the second set 317 of second antenna elements 223 and thethird set 318 of third antenna elements 228 are spaced apart from eachother along the first direction 201. Thereby, the first set 315 islocated in between the second set 317 and the third set 318. The antennaelements 213, 223, 228 of the individual sets 315, 317, 318 are eachaligned in two rows along the second direction 202 so that theindividual sets 315, 317, 318 of antenna elements 213, 223, 228 formarrays with a narrow field of view along the second direction 202, whichis the elevation direction.

The first phase center 301 of the first antenna 211 comprising the firstand third set 315, 318 of antenna elements 213, 228 is located along thefirst direction 201 in between the first and third set 315, 318 ofantenna elements 213, 228 and the second phase center 302 of the secondantenna 221 comprising the first and second set 315, 317 of antennaelements 213, 228 is located along the first direction 201 in betweenthe first and second set 315, 317 of antenna elements 213, 223.

With the radar devices 1 described in connection with the previousFigures, the antenna signals occupying separate frequency bands arerouted between the radar circuit 100 and the antenna device 200 viacommon signal ports 130, 131, 133, 135, 136, 137 of the radar circuit100.

FIG. 28 shows such an alternative embodiment of a radar device 1according to the present disclosure. As far as no differences aredescribed or apparent from the Figures, the radar device shown in FIG.28 is configured as it is disclosed in connection with the radar device1 shown in FIG. 1.

With the radar device 1 shown in FIG. 28, each individual antenna 211,221 is connected to a separate signal port 138. The individual signalports 138 route transmit radar signals 19 and receive radar signals 29that constitute single antenna signals for the connected antennas 211,221. Thereby, the radar signals 19, 29 routed to the first antennas 211occupy the first frequency band and the radar signals 19, 29 routed tothe second antennas 221 occupy the second frequency band. Fordetermining the target distance, the signal processing device 120 of theradar device 100 is configured to jointly process the antenna signalsthat occupy the first frequency band and are transduced via propagationchannels 70, 72, 74, 76 established between first antennas 211 and theantenna signals that occupy the second frequency band and are transducedvia propagation channels 71, 73, 75, 77 established between secondantennas 221.

FIG. 29 shows an alternative embodiment of a first and second antenna211, 221 of an antenna device 200 according to the present disclosure.As far as no differences are described or apparent from the Figures, theembodiment shown in FIG. 29 is configured as it is disclosed inconnection with the embodiment shown in FIG. 7 and vice versa.

The first antenna 211 and the second antenna 221 are both coupled via asignal routing device 230 to a common signal port 204 of a radar circuit100. The radar circuit 100 is configured to route the radar signal shownin FIG. 20 over the common signal port 204, which radar signal has thefirst signal portion 11 occupying the first frequency band 31, thesecond signal portion 12 occupying the second frequency band 34 and thethird signal portion 13 occupying the third frequency band 37.

The first antenna 211 is configured to transduce the first and thirdsignal portions 11, 13, but not the second signal portion 12 and thesecond antenna 221 is configured to transduce the second and thirdsignal portion 12, 13, but not the first signal portion 11. To this end,the first antenna 211 is coupled via a first filter 281 of the signalrouting device 230 to the common signal port 204 and the second antenna221 is coupled via a second filter 282 of the signal routing device 230to the common signal port 204. The first filter 281 is configured topass the first and third signal portion 11, 13 and to block the secondsignal portion 12, while the second filter 282 is configured to pass thesecond and third signal portion 12, 13 and to block the first signalportion 11.

The first antenna 211 comprises a first set 315 of first antennaelements 213 and the second antenna 221 comprises a second set 317 ofsecond antenna elements 223. The first set 315 and the second set 317are spaced apart from each other along a first direction 201. Thisresults in a first phase center 301 of the first antenna 211 beingcentered at the first set 315 of first antenna elements 213 and a secondphase center 302 of the second antenna 221 being centered at the secondset 317 of second antenna elements 223. The first and second phasecenter 301, 302 are therefore spaced apart from each other along thefirst direction 201.

Since the third signal component 13 is transduced via both the first set315 of first antenna elements 213 and the second set 317 of secondantenna elements 223, the third signal component 13 is transduced via athird phase center 303 that is located in between the first and secondphase center 301, 302 along the first direction 201.

Additionally, the first antenna 211 is configured to transduce the firstand third signal portions 11, 13 having a first linear polarization,which is parallel to the first direction 201, and the second antenna 221is configured to transduce the second and third signal portions 12, 13having a second linear polarization, which is parallel to a seconddirection 202 that is perpendicular to the first direction 201. Thisresults in the third signal portion 13 being transduced with a thirdpolarization that is a linear superposition of the first and secondpolarization. The third polarization may be a linear polarization at anintermediate direction between the first direction 201 and the seconddirection 202, for example at a direction that has an angle of +/−45°with the first and second direction 201, 202. Alternatively, the thirdpolarization may be an elliptical polarization.

FIG. 30 shows an alternative embodiment of the antenna device 200 shownin FIG. 29. With the antenna device 200 shown in FIG. 30, the first,second and third phase center 301, 302, 303 coincide at the center ofthe first set 315 of first antenna elements 213. This is achieved by thesecond antenna elements 223 of the second antenna 221 being placedsymmetrically on both sides of the first antenna elements 213 of firstantenna elements 213 along the first direction 201. Consequently, thefirst, second and third signal portion 11, 12, 13 of the radar signalrouted via the common signal port 204 are all transduced via the samephase center. However, a first propagation channel established by thefirst signal portion 11, a second propagation channel established by thesecond signal portion 12 and a third propagation channel established bythe third signal portion 13 all have different polarizations, as well asdifferent gains and fields of view along the first direction 201.

FIG. 31 shows a method 400 performed by the radar devices 1 according tothe present disclosure. The method comprises transceiving antennasignals by generating 405 the first antenna signals occupying the firstfrequency band and the second antenna signals occupying the secondfrequency band with the transmit chains 125, 126 of the signal generator105 of the radar circuit 100. The method then comprises routing 410 theantenna signals via signal ports 130, 131, 133 to the antenna device200. The method 400 further comprises transducing the first and secondantenna signals with the antenna device 200 by radiating 415 the firstantenna signals via the first transmit antennas 211 and the secondantenna signals via the second transmit antennas 221.

The method 400 then comprises transducing the first antenna signals byreceiving 420 the first antenna signals via the first receive antennas211 and the second antenna signals via the second receive antennas 221of the antenna device 200, respectively. The method further comprisesrouting 425 the antenna signals from the antenna device 200 via thereceive signal ports 135, 136, 137 to the radar circuit 100. The methodfurther comprises measuring the received antenna signals by generating430 the data signals 123, 124 representing the received antenna signalswith the receive chains 127, 128. The method further comprisesevaluating the radar signals 20, 25 by jointly processing 445 the firstand second antenna signals to determine the distance to the targetobject and by differentiating 440 individual propagation channels usingthe separability parameter of the antenna signals.

FIG. 32 depicts a vehicle 500 that is equipped with a radar device 1according to the present disclosure. In the embodiment shown in FIG. 32,the radar device 1 is configured as a front radar of the vehicle 1 and aradiation field 501 of an antenna device of the radar device 1 isdirected in the forward direction of the vehicle 500. The radar device 1is part of a vehicle control system 502 of the vehicle 500 and isconnected to a control device 504 of the vehicle control system 502. Thecontrol device 504 is configured to perform advanced driver's assistfunctions, such as adaptive cruise control, emergency brake assist, lanechange assist or autonomous driving, based on data signals received fromthe radar device 1. These data signals represent the positions of targetobjects in front of the radar device 1 mounted to the vehicle 500. Thecontrol device 504 is configured to at least partly control the motionof the vehicle 500 based on the data signals received from the radardevice 1. For controlling the motion of the vehicle, the control device504 may be configured to brake and/or accelerate and/or steer thevehicle 500.

What is claimed is:
 1. A radar device for automotive applications, theradar device comprising: a radar circuit configured to transceive afirst antenna signal and a second antenna signal, wherein the firstantenna signal occupies a first frequency band and the second antennasignal occupies a second frequency band that is separate from the firstfrequency band; an antenna device configured to transduce the firstantenna signal via a first antenna of the antenna device and the secondantenna signal via a second antenna of the antenna device; and a signalprocessing device that comprises a ranging module that is configured tojointly process the first antenna signal and the second antenna signalto determine a distance to a target object irradiated by the antennadevice.
 2. The radar device according to claim 1, wherein the signalprocessing device is configured to separately process the first antennasignal and the second antenna signal to detect, from the first antennasignal, first target reflections via a first propagation channel, and todetect, from the second antenna signal, second target reflections via asecond propagation channel.
 3. The radar device according to claim 1,wherein the first antenna signal comprises a first frequency sweepwithin the first frequency band, and wherein the second antenna signalcomprises a second frequency sweep within the second frequency band. 4.The radar device according to claim 3, wherein a slope of the firstfrequency sweep equals a slope of the second frequency sweep.
 5. Theradar device according to claim 1, wherein the radar circuit isconfigured to transceive a third antenna signal that occupies a thirdfrequency band that is different from the first frequency band and thesecond frequency band, and wherein the ranging module is configured tojointly process the first antenna signal, the second antenna signal, andthe third antenna signal to determine the distance to the target objectirradiated by the first antenna signal, the second antenna signal, andthe third antenna signal.
 6. The radar device according to claim 5,wherein the third frequency band lies between the first frequency bandand the second frequency band,
 7. The radar device according to claim 6,wherein the third frequency band covers an entire frequency rangebetween the first frequency band and the second frequency band.
 8. Theradar device according to claim 5, wherein the antenna device isconfigured to transduce the third antenna signal via both the firstantenna and the second antenna.
 9. The radar device according to claim1, wherein the antenna device is configured to transduce the firstantenna signal with a first polarization, and to transduce the secondantenna signal with a second polarization, and wherein the secondpolarization is different from the first polarization.
 10. The radardevice according to claim 9, wherein the second polarization isorthogonal to the first polarization.
 11. The radar device according toclaim 1, wherein the signal processing device is configured to processthe first antenna signal to form a first virtual array of antennas alonga first direction, and wherein the signal processing device isconfigured to process the second antenna signal to form a second virtualarray of antennas along a second direction.
 12. The radar deviceaccording to claim 1, wherein the first antenna has a first field ofview, the first field of view having a first extent along a lateraldirection, wherein the second antenna has a second field of view, thesecond field of view having a second extent along the lateral direction,and wherein the first extent is larger than the second extent.
 13. Theradar device according to claim 1, wherein the antenna device isconfigured to capture target reflections of the first antenna signalfrom target positions within a first range, and to capture targetreflections of the second antenna signal from target positions within asecond range, and wherein the first range is smaller than the secondrange.
 14. The radar device according to claim 1, wherein the secondantenna comprises at least some of antenna elements of the firstantenna.
 15. The radar device according to claim 14, wherein the secondantenna comprises all of the antenna elements of the first antenna. 16.The radar device according to claim 1, wherein a first antenna elementthat is part of the first antenna and a second antenna element that ispart of the second antenna are both coupled to a common signal port ofthe radar circuit, wherein the radar device is configured to route boththe first antenna signal and the second antenna signal via the commonsignal port between the radar circuit and the antenna device, andwherein the antenna device is configured to transduce the first antennasignal via the first antenna element and not via the second antennaelement, and to transduce the second antenna signal at least via thesecond antenna element.
 17. A system comprising: a vehicle with a radardevice, the radar device comprising: a radar circuit configured totransceive a first antenna signal and a second antenna signal, whereinthe first antenna signal occupies a first frequency band and the secondantenna signal occupies a second frequency band that is separate fromthe first frequency band; an antenna device configured to transduce thefirst antenna signal via a first antenna of the antenna device and thesecond antenna signal via a second antenna of the antenna device; and asignal processing device that comprises a ranging module that isconfigured to jointly process the first and second antenna signal todetermine a distance to a target object irradiated by the antennadevice.
 18. The system according to claim 17, wherein the signalprocessing device is configured to separately process the first antennasignal and the second antenna signal to detect, from the first antennasignal, first target reflections via a first propagation channel, and todetect, from the second antenna signal, second target reflections via asecond propagation channel.
 19. The system according to claim 17,wherein the first antenna signal comprises a first frequency sweepwithin the first frequency band, and wherein the second antenna signalcomprises a second frequency sweep within the second frequency band. 20.A method for operating a radar device, for example for automotiveapplications, the radar device comprising a radar circuit, an antennadevice and a signal processing device, the method comprising:transceiving a first antenna signal and a second antenna signal with theradar circuit, wherein the first antenna signal occupies a firstfrequency band and the second antenna signal occupies a second frequencyband that is separate from the first frequency band; transducing thefirst antenna signal via a first antenna of the antenna device and thesecond antenna signal via a second antenna of the antenna device; andjoint processing of the first and second antenna signal with a rangingmodule of the signal processing device to determine a distance to atarget object irradiated by the antenna device.